Primaries might also contribute to party transformation by incentivizing candidates to move position within an election cycle. Candidates might face a “strategic positioning dilemma” if they must first satisfy an extreme selectorate to earn the nomination before facing a comparatively moderate general electorate. This chapter therefore tests whether all candidates in a primary adapt their positions away from the center during the nomination phase of a single election cycle, presenting general election voters with polarized choices. To scale positions both during and after a primary it uses a text-as-data approach based on candidates’ communication on Twitter during the 2020 election cycle. It finds that Democratic candidates who lost primaries became significantly more moderate immediately after their defeat, especially if they lost in ideological or factional primaries. It does not observe this pattern among Republican losers. This chapter demonstrates a further way in which primaries may contribute to polarization, incentivizing candidates to adopt positions further from the ideological center during the nomination phase of the election cycle.

This chapter identifies why the descriptive changes observed in Chapter 2 took place. To answer this question, it proposes a model of structural change being responded to by the key actors during the nomination process. These structural changes are grouped into three categories: changing electoral incentives, new regulatory reforms, and technological developments. These changes elicited responses from actors within the party network in terms of organizational structure and electoral strategy, by candidates in terms of whether and how they ran for office, and among voters in terms of their participation and motivation in nationalized congressional primaries.