Fifteen Eighty Four

In an era of increasing partisan conflict and ideological division in the U.S. Congress, primary
elections are frequently blamed. In my new book, Party Transformation in Congressional
Primaries: Faction and Ideology in the Twenty-First Century, I explore how the dynamics of
primary competition fundamentally changed in recent decades, contributing to the ideological
polarization of parties in Congress. Through original research of all congressional primary
elections between 2006 to 2020, I demonstrate that factional and ideological competition within
parties have become more prominent during the twenty-first century. Yet, I also show that
ways these contests matter for partisan polarization are more nuanced than commonly
conceived.

For decades, the central narrative surrounding primary elections has fixated on blaming
“extreme” primary voters for electing ideologically proximate candidates. Yet, my findings
challenge this conventional wisdom. Contrary to popular belief, I show that primary voters do
not systematically prefer non-centrist candidates. Instead, the influence of primaries lies in the
evolving behaviors of candidates and other important stakeholders in the party network, such
as interest groups and partisan media.

Congressional primaries have often shifted from low-salience contests—often focused
on candidate competence and local issues—to become ideological battlegrounds. Factional
alliances and ideological positioning now dominate these contests. These factions, such as
progressive Democrats or reactionary Republicans, amplify intra-party divisions and
incentivize candidates to adopt extreme positions, not because voters demand it, but due to
the pressures of party networks and elite actors in the party.

The book demonstrates that the Republican Party experienced a transformation in its
primary landscape earlier and to a greater degree, with the rise of the Tea Party and
subsequent reactionary factions altering the party’s internal composition. By 2010, Republican
primaries were a focal point of ideological conflict, pulling the party further to the right. In
contrast, this narrative only became pronounced in the Democratic Party after 2018, spurred
by progressive challenges to establishment candidates in response to the Trump presidency.
These dynamics underscore a critical asymmetry in how primaries continue to affect the two
major parties today, with the Democratic Party organization more willing and able to act in
ways that affect the outcomes of nomination contests.

The book identifies and tests three key mechanisms through which primaries influence
party transformation:

▪ Selective Effect: This widely discussed mechanism posits that primary voters prefer
ideologically extreme candidates. My analysis shows that this effect is limited to
incumbent races, with voters often selecting candidates closer to the center in other
contests.
▪ Between-Election Adaptive Effect: Incumbents receiving factional or ideological
primary challenges adjust their legislative behavior in subsequent congresses to appeal
to the (perceived) preferences of primary constituents. This results in long-term shifts
toward ideological poles, particularly among Republicans.
▪ Within-Election Adaptive Effect: During contested primaries, I find evidence that some
candidates strategically adopt extreme positions to appeal to their primary electorate.
These positions often persist into the general election, presenting voters with more
polarized choices than they might otherwise prefer.

Understanding the transformation of congressional primaries is helps understand both
whether and how the nomination contest relates to the broader forces driving polarization in
American politics. As the book demonstrates, primaries have become arenas where party
factions battle for control, shaping not only the candidates who run but also the policies they
advocate for. Yet, this change has not emanated bottom-up from the preferences of primary
voters. The book therefore calls for a shift in how scholars, journalists, and policymakers
approach the issue of primary polarization. Rather than focusing exclusively on voters, we
must examine the roles of candidates, party elites, and external influencers. Reform efforts,
such as moves to change the structure of primaries to encourage moderation, must be informed
by this more nuanced understanding of the forces at play.

As we navigate an era of political upheaval, I believe that the questions and results
that emanate from Party Transformation in Congressional Primaries are more relevant than
ever. I invite readers, scholars, and practitioners to engage with these findings and contribute
to the ongoing dialogue about the health of American democracy.