Primary Elections and Partisan Polarization in the U.S. Congress

Abstract

Many observers and scholars argue that primary elections contribute to ideological polarization in U.S. politics. We test this claim using congressional elections and roll call voting behavior. Many of our findings are null. We find little evidence that the introduction of primary elections, the level of primary election turnout, or the threat of primary competition are associated with partisan polarization in congressional roll call voting. We also find little evidence that extreme roll call voting records are positively associated with primary election outcomes. A positive finding is that general election competition exerts pressure toward convergence as extreme roll call voting is negatively correlated with general election outcomes.