On the relationship between party polarization and citizen polarization

Do party policy offerings simply reflect public opinion or do parties shape public demand for policies? Theories of party position-taking and the operation of democracy expect parties to track their supporters’ positions, while scholarship of public opinion has shown voters often adopt the position of their preferred parties. We apply both of these theoretical expectations to the relationship between citizen polarization and party polarization and additionally argue that the relationship between them should be stronger among politically more engaged and sophisticated citizens. We draw on aggregated survey data from 174 cross-national and national election studies from 19 established democracies, to assess the extent to which citizen polarization responds to party polarization, the extent to which parties respond to changes in citizen polarization, and whether these relationships differ across different groups of citizens. We estimate seemingly unrelated error-correction models employing data on party and citizen positions from 1971 to 2019. Our findings suggest that citizen polarization follows party polarization and also that politically engaged and sophisticated citizens are more responsive to changes in party polarization than the politically less engaged and unsophisticated. In contrast, we find little evidence that party polarization responds to changes in citizen polarization.