Intraparty Ideological Disagreement in Congressional Nomination Processes

In recent decades, academics have been in broad agreement that elites in Congress have polarized. This has led scholars to argue that due to elite sorting, the parties have become ideologically homogenous, with evidence in roll call voting behavior and party unity in Congress. At the same time there has been renewed interest among voters in the congressional nomination process, with participation increasingly significantly over the past decade. This period also saw increased attention on questions about the ideological identity of each of the major parties, with specific focus on internal ideological division. The current literature on polarization, which suggests that the parties have become more ideologically uniform, is unable to explain either of these recent trends. In understanding parties as homogenous, we fail to understand the diversity of ideological preferences within the parties or the drivers of internal party competition, particularly in the congressional nomination process. This thesis utilizes an original dataset to show that during the period 2006-2018 these contests transformed into factional primaries; ideologically motivated competitions between organized factions. This represents a shift in the reason for intraparty competition, with races previously dominated by valence factors such as competence, prior experience in public office, or ability to win the general election for the party. As the parties have become more distinct, space has opened for intraparty ideological disagreement at an elite level. While intraparty differences were previously regional, party factions have now nationalized meaning this diversity is present within individual congressional districts. Structural changes including new groups entering the parties and participating in the nomination process have made ideology a more prevalent feature, suggesting that factional primaries look likely to be a long-term trend. This has been amplified by changes in electoral incentives for the parties, and tactical behavior on the part of candidates and voters alike.