Not Of Primary Concern: Stability, Ideology, and Vote Choice in U.S. Primaries, 2008-2024

Abstract

America's major political parties have been riven by ideological factions which contest for power partly through partisan primaries. Ideological factions can only be grounded in voting behavior to the extent that primary voters are consistently ideological across primaries. Yet, prior research has relied overwhelmingly on cross-sectional analyses. This paper thus provides new, over-time evidence on the extent of ideological voting in partisan presidential and Senate primaries. It first uses population-based panel data which measures the same respondents' presidential primary preferences in 2008, 2016, and 2020 to investigate ideology's role in stabilizing primary vote choices. Across pairs of primaries, over one third of respondents prefer candidates representing different ideological factions within the same party. To extend these analyses to Senate races and address concerns about sampling biases, it also draws on precinct-level returns in five states' primaries (2008-2024). Evidence from these varied sources points to one conclusion: ideological considerations influence primary voting, but their modest association with vote choice and limited over-time stability leaves substantial room for other factors.

Keywords: Primaries, voting, ideology, panel data, stability

JEL Classification: H00, H40