Replacing the Establishment: When Primary Insurgents Win

• In Event: Understanding the Drivers of Polarization

Abstract

Ideological insurgents also reshape the party by supporting a primary challenger who defeats the incumbent, or the establishment-favored candidate in an open-seat race. Although incumbents almost always win (Boatright 2013), and establishment-favored candidates win in about two-thirds of open seat races (Hassell 2017), ideological challengers who win the nomination despite opposition from party elites can have an outsized effect on how the party operates in Congress. Since leaders prioritize legislation that does not divide the party (Cox and McCubbins), even a small increase in ideologically extreme members can cause party leaders to prioritize significantly more ideological policy goals. I will closely examine how these legislators won office by defeating an establishment-favored candidate—i.e. Ted Cruz, Mike Lee, Rand Paul, Bernie Sanders, Marjorie Taylor-Greene, AOC, David Brat—have an outsized influence on polarization. Relatedly, the prospect of an ideological challenge can prompt a more moderate legislator to retire prematurely, leaving an open seat in which the forces described above will be at play.
In this chapter, I use DW-Nominate to compare the ideology of successful insurgents to the incumbents that they defeat. I then developed a simple model to “forecast” how polarized Congress would be in each session, if all of those incumbents had defeated their ideological primary opponent.
I apply a similar approach to open seat races, but with a few additional steps on the front end. First, I identify the establishment’s preferred candidate in the open seat primary election. Next, create an index that estimates DW-Nominate scores (which only exist for candidates who actually win a congressional seat) based on Adam Bonica’s ideology scores for all federal candidates (including those who do not win a congressional seat). This index allows me to estimate how the level of polarization would be different if the establishment’s preferred candidates won every openseat primary.

Author

• Richard C Barton, Syracuse University