Notes on Madison’s Constitution Under Stress: A Developmental Analysis of Political Polarization

Introduction

Modern political analysis often views the American political system as tending towards moderation and stability.
Some analyses emphasize the stabilizing effect of Madisonian institutions with their fragmented and overlapping authority within a diverse society.
Others highlight the incentives for a two-party system to operate near the center of the electorate's preferences.
Both approaches suggest resistance to major parties staking out positions without broad support.
The rise of durable polarization has challenged these frameworks.
The absence of correction in polarization has led to the acknowledgment of a shift from low to high polarization.
Political scientists have worked to understand the characteristics of this new setting and the forces that created it.
Some argue that the long period of polarization reaffirms the flexibility of the Madisonian framework, citing historical precedents and the symbolic nature of partisan divisions.
However, it's important to consider the conditions under which polarization might be self-perpetuating, with new developments encouraging further polarization.
The self-correcting mechanisms of the Madisonian system may have weakened or become engines of polarization.
A developmental approach is needed, treating polarization as an ongoing process. This requires examining institutional configurations that can dampen or exacerbate polarization.
Meso-institutions once fostered factional divisions within parties, undermining polarization. Today, they have been transformed, intensifying divisions.
Many actors now see their interests as tied to their party's success, contributing to a nationalized, polarized politics.
This contrasts with the standard Madisonian story of stability reinforced by political institutions and culture.
A developmental analysis directs attention to the meso-institutional environment, clarifies the features that traditionally limited polarization, helps analyze asymmetrical polarization, and connects American politics to comparative politics on democratic backsliding.

Historical Perspectives on Polarization

Historical comparisons can offer a counterpoint to the perception of today’s politics as unprecedented.
Historical evidence often highlights the distinctiveness of recent developments, particularly the self-reinforcing nature of polarization.
A key question is whether today’s party divisions are unprecedented.
Analyses often focus on congressional roll call voting, such as Poole and Rosenthal’s Nominate methodology.
Nominate scores compare the ideology of the median Democrat and Republican, or the percentage of partisans closer to the other party’s center.
Studies suggest that Congress is now more polarized than at any time since the end of Reconstruction.
Even with high polarization scores, some argue that polarization is the normal state of affairs in American politics, with the 1930s–1970s being an exception.
Others suggest that intense party conflict may well be the normal state of affairs, with the long postwar period of muted party conflict constituting a mere exception.
Nominate scores reveal voting differences but not the significance of the policy issues at stake.
Scholars have considered historical periods like the lead-up to the Civil War and the turn of the twentieth century as analogies for today’s politics.
Most observers believe that contemporary divisions are far less serious than those leading up to the Civil War.
However, the dangers posed when party divisions are overlaid on an intense sectional cleavage should not be overlooked.
The period of high party voting and centralized leadership in Congress spanning the late nineteenth and early twentieth century is often seen as the best analog for today.
Close party balance and the salience of racial concerns were critical sources of polarization in each era.
Analogies to specific periods break down when pushed too far.
The Civil War era was remarkably brief, with deep internal divisions on slavery up until the mid-to-late 1850s, and the new Republican majority became deeply divided over Reconstruction and key economic questions soon after the war ended.
The 1890–1910 analogy also has evident limitations, featuring serious regionally based intraparty divisions over economic development and regulatory policies.
Intense partisan polarization proved short-lived and deeply vulnerable to regionally based factional interests.
The vulnerability of previous episodes of polarization has led some to conclude that polarization will ultimately falter.
However, such a claim requires a careful identification and assessment of the mechanisms that either attenuate or intensify polarization.
It's important to consider the prospect that within contemporary party politics the institutional configurations that previously acted as countervailing mechanisms have been displaced by alternative structures that instead reinforce or even intensify polarization.

The Madisonian System: A Shield Against Polarization?

The dynamics of contemporary polarization raise important questions about the standard, Madisonian account of American politics.
The Founders were preoccupied with creating a stable republic.
Madison argued that American political institutions could prevent all-out conflict between competing camps.
Critical mechanisms that would tend to attenuate or countervail against polarization, rather than reinforce it, were built directly into the constitutional system.
Others, such as the development of decentralized and geographically factionalized political parties, were crucial (if unintended) outgrowths of the constitutional framework.
Separation of powers, checks and balances, and federalism divide power, making it less likely that any single group will gain control of the entire government.
Governance will routinely require accommodating a range of group interests.
The rules structuring elections also require building different kinds of coalitions for different offices, discouraging the emergence of a single coherent and dominant cleavage.
The creation of an extended republic with immense geographic diversity reinforced the institutional obstacles to polarization.
The scope of the new nation ensured a heterogeneity of viewpoints, which would make the emergence of a majority faction unlikely.
An extended republic would tend to give rise to cross-cutting cleavages.
Creating a majority would require broad appeals to widely shared interests, rather than narrow, parochial appeals to a particular faction.
Social pluralism, when combined with America’s fragmented constitutional structure, forces bargaining among diverse groups in order to achieve policy success.
Federalism interacts with the extended republic in critical ways.
The diversity of state circumstances and the relative autonomy of state political institutions promote carefully brokered compromises that are mindful of an array of distinctive interests.
These core institutions of American government tend to frustrate efforts to consolidate the power of a particular individual or coalition; each puts a premium on finding ways to accommodate opposing interests.
Even if one mechanism fails to operate in a particular context, there are built-in redundancies that reinforce the overall tendency toward stability and moderation.
These institutions have a homeostatic quality.
Politicians unwilling to engage in compromise are likely to trigger an increasingly powerful backlash.
The Framers did not anticipate the development of political parties.
Even so, the constitutional system profoundly shaped these new parties in ways that made them unlikely vessels for intensely and durably polarized politics.
American political institutions helped produce parties that were federal in character and decentralized in many of their operations.
American parties were “confederative,” consisting “of a working coalition of state and local parties” that provided pluralistic representation of diverse interests.
A critical source of power and independence for state parties has been their control of nominations and, more generally, their role in shaping career paths for ambitious politicians.
The need to compete for power across a wide span of very different states forced American parties to take the form of catch-all organizations that accommodated a range of ideologies and social groups.
While there also was an important national aspect to these party organizations, they retained substantial autonomy throughout much of their history.
American legislative parties “can rarely achieve the degree of party discipline that is common in parliamentary systems.”
This feature of party politics has historically lowered the stakes of political conflict.
Even if one party wins power, it is forced to accommodate a diverse array of interests that likely will make its ultimate policies broadly acceptable.
The cross-cutting cleavages and fluidity of alliances ensure that even if one’s side loses today, the outcome could easily change soon.
This account of the American political system always had critical blind spots.
It tended to overlook the systematic biases in representation and inequalities in social and economic power.
Institutionalized white supremacy was the most glaring refutation of this pluralist faith.
The Madisonian account also did not easily accommodate social movements.
The Civil War constitutes a crucial moment when the Madisonian system catastrophically failed to contain conflict.
But for all of these failures, the Madisonian system was, for much of American history, a robust obstacle to the consolidation of power.
The operations of the constitutional system might be remade on the ground over time by assertive presidents or new ideological formations, but the core features that gave rise to pluralism and fragmented power remained: separation of powers, checks and balances, territorially grounded representation, and the extended republic.
In sum, while political parties might bridge the differences across branches, institutions, or localities in a way that the Framers had not anticipated, sustained, intense policy polarization at the national level has been rare.
Even in periods of high party voting in Congress, there remained substantial intraparty divisions that limited the scope of partisan battles.
A fragmented party and interest group system meant that national party lines failed to capture or contain many of the critical disputes animating politics—and these disputes countered the force of national party polarization.
American politics scholars are not the only ones to highlight the impact of these features on the stability of American democracy.
The comparative literature on presidentialism also showed appreciation for the apparent robustness of the Madisonian system.
Presidential systems tend to be less stable due to dueling bases of legitimacy. Viewing the United States as an apparent exception, suggests that our weak and fragmented parties have prevented this kind of all-or-nothing showdown between branches under the control of competing parties.
However, confidence in the moderating influence of American political institutions may no longer be justified.

The Development of Modern Political Polarization

Standard accounts of polarization emphasize the sorting of the parties, at both the elite and mass levels, which flowed from realignment of the political parties around issues of race.
In national politics the critical events surrounding the parties’ repositioning on civil rights occurred in the 1960s and early 1970s.
By the end of this period, national party leaders had clearly placed themselves on the conservative and liberal sides of racial issues.
This new clarity in turn helped trigger the well-known processes of elite and mass sorting, and elite replacement, that analysts associate with modern partisan polarization.
A second development in the 1960s and early 1970s was also critical: a dramatic expansion and centralization of public policy.
Civil rights legislation was only the entering wedge.
During the long 1960s, liberal Congresses enacted major new domestic spending programs, greatly enlarged the regulatory state, and federal courts introduced or expanded a range of rights, which essentially nationalized policy making with respect to a host of controversial social issues.
By the late 1970s, Washington had become a much more prominent force, across a much wider range of issues, than it had been two decades earlier.
The expanded role of Washington became a critical issue dividing the parties, contributing to polarization both directly and indirectly.
Directly, it reinforced the process of sorting between the consolidating liberal and conservative parties.
Increasingly, the two parties diverged on fundamental questions regarding this emerging activist federal state.
Indirectly, this new government activism encouraged the mobilization and nationalization of interest groups in response to the growing stakes in national-level political contestation.
Over time these two dynamics merged.
These extensive and now nationalized groups faced growing incentives to align themselves with one party or the other.

The Transformation of Meso-Institutions

The initial development of polarization and of nationalized policy contestation had profound consequences for the American polity.
It encouraged changes in meso-institutions: interest groups, state parties, and the media.
In earlier eras, these arrangements had been crucial bulwarks of the formal institutions of our Madisonian system, tending to attenuate partisan polarization.
Today, they have changed in ways that instead encourage further national party polarization.
These changes help to account for an increasingly tribal mass politics marked by negative partisanship, which further intensifies polarization.

The Shifting Relationship Between Interest Groups and Parties

The expanding role of the national government led to a proliferation and nationalization of interest group activity.
The new environment produced a second major shift: a growing inclination of powerful groups to draw closer to one or the other of the major parties.
In an increasingly polarized environment, these groups faced incentives to pick a party—to try to achieve their policy goals by working with, and in support of, a durable political coalition.
Rather than being a source of incentives and action that cross-cut parties and thus restricted polarization, interest groups became another factor reinforcing the divide between them.
Some groups have always aligned closely with parties.
Yet core understandings of politics emphasized the strong incentives for most groups to avoid close alignment with parties.
There is broad consensus today that the interest group environment has become more polarized and party-aligned.
The list of prominent groups that have moved into tighter alliance with a single political party as the nation has polarized is long.
For Republicans it includes such influential organizations as the National Rifle Association (NRA), the Koch brothers network, the oil and gas industries, and major conservative Christian organizations.
The powerful US Chamber of Commerce provides a striking illustration of the broader trend.
The Democratic coalition has, since the New Deal, been aptly characterized as a coalition of distinct policy-demanding groups.
However, several key groups that had maintained substantial ties to both parties prior to the 1960s and 1970s are now more firmly tied to the Democratic Party.
The list would include major civil rights, environmental, and reproductive rights groups.
These growing attachments partly reflect the fact that as the parties polarized and offered clearer choices, more groups found one party’s policy preferences to be a much better fit than the other’s.
A second factor inducing groups to ally with one party is that the previously dominant strategy of maintaining a collection of friends in both parties became far less effective.
There used to be major bipartisan roads to policy making in Washington that did not run through the party leadership.
Party leaders now have much greater agenda control, and leaders look at which groups are solidly in their party’s corner.
The same incentives influence appointments to courts and regulatory bodies.
This tightening party control makes a party-based alliance far more valuable for groups.
The rise of negative partisanship further changes interest group incentives.
For a party’s core supporters, it has become increasingly suspect to work with politicians of the other party.
In such a setting, many groups will calculate that achieving their goals depends on helping their team win rather than reaching out to members of the other party.
There is a powerful self-reinforcing logic at play.
The deeper and more intense the partisan divide, the stronger the incentives for most interest groups to join a team, and the more closely aligned groups are with parties, the stronger the incentives for them to do all they can to help their team win.
As an interest group’s party moves closer to their preferred policy positions (and the other party moves in the opposite direction), the stakes in the outcome of interparty conflict increase.
As groups join teams, see increasing benefits of victory by their team, and thus work to insure those victories while punishing defectors, interest group political behavior can intensify polarization rather than moderating it.
The transformed interplay between groups and parties does more than just remove one of the traditional mechanisms that limit polarization.
Many of these contemporary groups are national in scope and invested in an ambitious policy agenda.
They eagerly push their partisan allies to advance that agenda wherever possible.
Groups may also depend on member mobilization strategies that rely on the intensification of conflict.
These tendencies have generated concern among analysts about a possible “hollowing out” of the parties.
Parties have contracted out mobilizing voters to groups, who may also have considerable influence over fundraising and candidate recruitment.
Party networks increasingly lack the kind of robust organizational infrastructure that might limit extremism.
Under conditions of polarization, they may cede power to groups that are more accepting of electoral risk to achieve potentially extreme ends.

Shifts in State Parties and Federalism

For much of its history, America’s federal party system tended to act as a countervailing mechanism limiting partisan polarization.
Even when the national parties were relatively polarized on a given set of issues—state and local parties provided a partially independent, geographically rooted power base to represent competing interests that cross-cut that division.
The geographically decentralized party system attenuated polarization by providing a mechanism to incorporate new interests that fit uncomfortably with existing national party coalitions.
American mass parties were premised as much on attempting to suppress issues that the two national parties preferred not to fight about as they were on highlighting the issues that neatly divided the parties.
Much of this political work was done through third parties with distinct geographic bases, though these parties’ efforts also pressured members of the two major parties to adapt.
National party polarization on economic issues was limited by regionally based intraparty cleavages that reflected sectionally distinctive political economies.
State parties provided a mechanism to represent these particular interests within each party.
The national parties lacked a veto over state party positions and over the entry of new groups into a party coalition, even when those positions and groups undermined an existing line of cleavage.
This process of geographically rooted factional entry repeatedly undercut partisan polarization.
Today’s state parties no longer are well situated to play this countervailing role.
Instead, they are far more integrated into national party networks in which key resources are outside the control of state party leaders.
Part of this story has involved strengthening formal coordinating mechanisms at the national level, such as the Democratic National Committee, Republican National Committee, and congressional campaign committees.
Nomination process reforms that empower ordinary voters have also shifted influence within states from professional, locally rooted politicians to policy-oriented activists who have often focused on hot-button issues that divide the parties nationally.
Fundraising has been nationalized.
The share of itemized campaign contributions that cross state lines went from 31% in 1990 to 68% in 2012.
The nationalization of politics, including of communication networks, has made it harder for state parties and politicians to tailor their identity to local conditions.
State parties themselves have increasingly come to mirror their national counterparts.
State party platforms are more similar across states and more distinctive across parties than in earlier eras.
Even when a state party finds a national position to be disadvantageous locally—they are more likely to avoid the issue than articulate a stance that departs from their national party.
These platform differences are finding their way into state policy.
State-level policies are increasingly polarized by party.
A national network of conservative interests has played an increasingly prominent role in shaping state policy agendas and legislation when Republicans gain power.
The decline in state party autonomy is reflected in the increased alignment of state and national election outcomes.
As with the transformed role of interest groups, these changes in state party politics help make polarization self-reinforcing.
When it became harder for state politicians to distinguish themselves from the national party brand in the eyes of voters, their incentives began to change.
State politicians may well come to see their ambitions as tethered more closely to their status in the national party than their ability to cater to the state’s median voter.
When an issue potentially separates the state’s median voter from the position of the national party, politicians’ incentives to toe the national party line are likely to be stronger as voters prove less attentive to state-level differences and as the relevant audience for their behavior (interest groups, donors, etc.) becomes more nationalized.
State-level politicians will have an incentive to highlight national cleavages where their party has an advantage in their state, again furthering the polarization spiral.
What were once relatively autonomous state and local party organizations that provided a basis for dissident factions to form and challenge national party lines now appear to “be rather small cogs” in a nationally oriented network.
Within this new more integrated system, state-level politicians find it in their interest to reinforce or even intensify existing national alignments.

Transformation of the Media

The presence of news outlets that are allied with a party or ideological cause is nothing new in American history.
Nineteenth-century newspapers were, in many cases, clearly associated with parties, and often embraced sensationalistic material attacking the other party.
Even so, the party press of the nineteenth century was not nationalized.
Case study evidence suggests that voters in different regions who belonged to the same party did not necessarily receive the same messages about key issues.
Today’s media landscape is more dominated by national news.
This is primarily a matter of audiences shifting away from print newspapers and local television news sources, which, due to their geographic boundaries, continue to provide more state and local coverage than do other kinds of media sources.
The net result, however, is reduced information and engagement with state and local politics on the part of voters, which reinforces politicians’ incentives to focus on national issues and cleavages.
These changes may contribute to increasing the salience of nationally oriented political and social identities, in contrast to geographically rooted identities, furthering the trends toward nationalization and polarization.
Technological and commercial developments encourage the growth of an “outrage industry” that appeals to partisans.
This industry has powerful incentives to intensify polarization in two respects.
First, it attracts an audience by inflaming negative views about political opponents and making exaggerated claims about the political stakes involved.
Second, it holds its audience by delegitimating other sources of information
To the extent that a party’s voters come to rely on media outlets with incentives to polarize, and increasingly treat alternative sources of information as illegitimate, polarization is likely to become more intense and durable.

The Landscape of Modern Polarization

A developmental perspective emphasizes that processes of polarization and nationalization have been deeply intertwined over the past half century.
To understand polarization, many have, understandably, focused on southern realignment.
Among other effects, this created more of a 50–50 nation, increasing incentives for elite partisan behavior to gain an advantage in the tightly contested battle for majority control.
The southern realignment can be viewed as the starting point for many, if not all, of the linked transformations we have discussed.
It turned the GOP into a party whose base of rural evangelical whites tended to take the conservative position on a wide range of social and cultural issues, in addition to race.
The growth of the role of the federal government meant that more was at stake in politics.
In response, groups got stronger and became more focused on controlling outcomes at the federal level.
The more the parties diverged over increasingly consequential things, the more it mattered which side won.
As new issues came on the agenda, the push for Republicans to take the conservative side and Democrats the liberal side became stronger.
Due to the changing demographic/geographic bases of the parties and the growing incentives for both voters and groups to stay aligned with parties, guns, abortion, gay rights, and feminism all got absorbed into the party system in the same direction.
All of this induced yet further changes in the organizational landscape and incentives for interest groups, state parties, and the media.
These coevolving forces have, in part through their impact on these meso-institutions, fundamentally changed the way the American polity fits together.
In many cases, they did not just weaken the traditional generators of Madisonian pluralism; they transformed them into generators of intensified polarization.
Interest groups and issues do not cross-cut; they stack, one on top of the other, along partisan lines.
When new issues arise, existing groups, as well as politically aligned (and increasingly national) media, have incentives to push them into existing lines of cleavage.
Geography no longer encourages pluralism, as it often did even during what are typically characterized as highly partisan eras.
If state party competition focuses on intrastate dynamics, it will tend to be multidimensional, distinctive across states, and a source of moderation and plausible bipartisanship at the national level.
However, where media and interest groups are nationalized (and help create incentives for local parties to exploit even modest geographically based partisan inequalities), the role of geography may reverse.
Nationalization puts the focus of state politics on the main national dimension, which means that even modest geographically based partisan inequalities may intensify over time.

The Link to Mass Behavior

The meso-level changes in the organizational landscape are critical to understanding how polarization could become more intense over time.
These organizational changes have important ramifications not only for elite behavior but also for mass opinion and behavior.
Growing polarization produced several dynamics at the level of voters that reinforce polarization.
One critical aspect has been the stacking of cleavages in a manner that encourages tribalism.
In contrast to the cross-cutting cleavages that attenuated the intensity of mass-level divisions in the past, social identities now line up more crisply with partisan divisions, including race, ideology, geography, religion, and education.
This alignment—and the associated degradation of cross-cutting social ties—has turned partisanship into a “mega identity.”
Social sorting is self-reinforcing.
When a range of social identities all push in a single direction, it becomes much easier to see one’s opponents as socially distant and deserving of hatred.
Numerous studies have documented the increase in “negative partisanship” and “affective polarization” that is evident as more voters associate the other party’s adherents with social groups that they dislike.
Mass polarization may short-circuit the system’s traditional Madisonian features.
The pull of the median voter in incentivizing politicians to avoid extreme positions depends on citizens penalizing candidates when they move away from the center.
But if there are fewer swing voters, this pull toward the center will weaken.
When an increasing share of voters see the other party as an alien force hostile to their core values, the willingness to punish one’s own party’s politicians for taking an extreme position will weaken accordingly.
Parties have always sought to capitalize on an electoral “blind spot” that allows them to serve intense policy demanders without alienating voters.
When voters are more clearly sorted into enemy camps defined by stacked social identities, the size of this blind spot grows, weakening one of the most important self-correcting mechanisms to high polarization.

Implications

Conceptualizing polarization as a dynamic process has four important implications:
- It directs our attention to the meso-institutional environment of the American polity.
- It highlights the potential that these dynamic effects may disrupt the operation of self-correcting or countervailing processes.
- It helps us account for and analyze asymmetrical, or party-specific, aspects of polarization.
- It provides a firmer analytic foundation for exploring the potential for democratic backsliding in the American polity.

The Significance of Meso-Institutions

The initial polarization of American politics triggered broad changes in major interest groups, state parties and governments, and media.
These social arrangements are not formal (constitutional) rules, yet they play a crucial and often underappreciated role in mediating interactions among American citizens, among political elites, and between elites and ordinary citizens.
Considering these meso-institutions is especially vital when we seek to explain large-scale political change, since the formal institutions of American politics are, for the most part, fixed.
Over the past generation, changes in these meso-institutions have generally worked to intensify partisan polarization.

The Weakening of Self-Correcting Mechanisms

A striking feature of earlier periods of polarization is the extent to which meso-institutions operated as countervailing mechanisms that (often quickly) dampened the intensity and breadth of partisan warfare.
Within a fragmented, pluralist polity, partisan pushes away from centrist or consensus positions, in support of more distinctive and aggressive policy agendas, have tended to generate a reaction.
These reactions did not simply depend on the median voter’s political moderation.
Instead, they worked through the meso-institutional features, often primarily within parties rather than (as Downs postulated) between parties through the constraints directly imposed by electoral competition.
In large part because of the incentives created by institutional design, parties have been pluralistic and resistant to central direction.
This pluralism has reflected the competing concerns of interest groups, geographically diverse state parties, locally embedded media, and the distinct institutionally derived interests of politicians situated in different positions within our fragmented system of political authority.
If polarization helps transform these intermediary institutions and their associated incentives, however, these self-correcting processes may cease to operate.
When interest groups have strongly committed to a party and regard the stakes of party defeat as very high, they may find it prohibitively costly to push back against unwanted initiatives.
State parties, operating in an increasingly nationalized system of incentives, may cease to produce the political diversity that would generate backlash.
A developmental analysis of polarization points to a more complex view of causal relationships in a polity.
We should not assume that if X later returns to a prior value, it will have the same impact on Y, because the initial change in X may have had important effects on other variables as well.
A central contribution of developmental analyses is to push us to question simple, symmetrical notions of causality in which the relationship between X and Y is fixed over time and across contexts.
In fact, many of the developments that have been triggered or accelerated by polarization may be very difficult to reverse.

The Analysis of Asymmetrical Polarization

In recent years, Americanists have grappled with growing evidence that polarization is asymmetrical: The Republican Party has made a much more pronounced shift toward extremism.
For conventional models celebrating the political dominance of the median voter, such asymmetry constitutes a considerable puzzle.
Exploring how polarization develops over time offers traction on this puzzle in two respects.
- First, it clarifies why a party’s movement away from the center might not be self-correcting, even if the opposition party is not moving as far or as fast.
- Second, appreciating the developmental elements of polarization may provide leverage for understanding the sources of asymmetry between the parties.
Many frameworks for studying American politics are institutionally “thin,” focusing on the mass electorate and a set of formal institutions structuring competition between elites.
These thin formulations are almost intrinsically symmetrical, since competing teams of elites operate within the same rule structure and face the same electorate.
Once we incorporate meso-arrangements, the presumption of symmetry makes less sense.
Instead, we can see the possibility that different parties face different structures, and therefore their incentives and behavior may differ as well.
For reasons rooted in differences in party coalitions, ideological orientations, and historical trajectories, these meso-arrangements do in fact look quite different for the two major political parties.
As the conservative media ecosystem, developing partly in response to the perception of mainstream media bias, created new outlets that were explicitly tied to conservative organizations and causes, and focused on discrediting alternative sources of information.
The media ecosystem on the right is far more isolated from the informational mainstream than that of the left.
As with interest groups, partisan media on the right has become tightly intertwined with the GOP, with increasingly open coordination and exchange of personnel.
Although empirical research on the interest group side is less developed, these differences seem likely to exist there as well.
An important contributor to the asymmetry may be the shift of political resources to the wealthy and corporations that has accompanied rising income inequality.
This shift has different effects on the two parties, accelerating polarization in the GOP while introducing an important cross-cutting cleavage for the Democrats.
In addition, a number of the Madisonian countervailing mechanisms that limited polarization in the past may remain more relevant on the Democratic side.
The growing concentration of Democratic voters in urban areas is, within the American electoral framework, politically inefficient.
As a result, a Democratic victory in Congress requires winning red-leaning districts and states, creating an incentive to moderate and/or tolerate heterogeneity within the party.
Republicans, by contrast, receive an electoral bonus from this political geography, facilitating a move to the right.

The Risks of Democratic Backsliding

Exploring the dynamics of polarization may help equip Americanists to address an issue that comparativists have recently brought to the fore: the prospect that the United States may be vulnerable to “democratic backsliding”.
Backsliding—the gradual undermining of rules, norms, and pluralistic organizational arrangements that sustain open political contestation—is a dynamic process.
True, American politics has been polarized since the early 1990s, but many of the key features of the polity, as well as the nature of partisan competition, are now quite different.
The early 1990s preceded the development of the electoral weaponry that has further nationalized American politics, from Super-PACs to Fox News.
In short, the social infrastructure that can deepen animosity between the parties and diminish the prevalence or impact of countervailing pressures is far more developed than it was two decades ago.
Prominent analysts of American politics have questioned the challenges to democratic stability by emphasizing that the parties may not be as far apart as their rhetoric or roll call votes make them appear.
From this perspective, conflict between the parties is often intense but not necessarily deep.
Fierce jockeying for majority status obscures consensus on basic questions of government, and there is little reason to anticipate that polarization will destabilize political arrangements.
A developmental perspective suggests that the prospects for bandwagoning are much greater in today’s GOP than they might have been a few decades ago.
Formidable, intensely partisan media have blossomed on the right.
Along with the growing role of intense organized groups like the Koch network, the NRA, and organized evangelicism, these media forces have fueled negative partisanship.
These conditions create new incentives for political elites to stick with their team on matters where previously they might have chosen to dissent.
We have already discussed why many of the stabilizing forces that traditionally were linked to these institutions seem much weaker today.
In fact, in some cases (as with federalism), these arrangements now introduce new polarizing elements.
Finally, the emergence of hyperpartisanship means that the check on authoritarian developments in the presidency that the Madisonian system relies on most, Congress, may not work.
Republican members of Congress face multiple incentives to bandwagon rather than resist.
The developmental perspective raises a disturbing prospect: Under conditions of hyperpolarization, with the associated shifts in meso-institutional arrangements and the growth of tribalism, the Madisonian institutions of the United States may make it more vulnerable to democratic backsliding than many other wealthy democracies would be.