Preventative Polarization: Republican Senators’ Positional Adaptation in the Tea Party Era

Abstract

Republicans in Congress have, by almost any measure, become significantly more conservative over the last 25 years. We propose that the changing pressures they face when seeking reelection helps explain this trend. Rather than moderating towards the general election median voter as they had previously done, Republican senators became more conservative when seeking reelection to avoid the emergence of, or mitigate the threat from, a primary opponent after the Tea Party emerged. We also show that at the height of the Tea Party era—the 111th to 113th congresses—retiring senators moderated their voting behavior, suggesting that their personal preferences were more moderate than their expressed preferences. During the Trump era, we report mixed results, suggesting that the threat posed by primary challengers was not solely ideological, though the new dynamics and behaviors that emerged in the Tea Party era have continued to shape the Republican Party in the Senate.