Concentrated but Misaligned: Trends in Voter Agreement on Party Ideology in the United States, 1972–2020

Political parties play a central role in American politics as electoral brands and sources of social identity. Although Americans increasingly recognize differences between the major parties, it is unclear whether they share a common view of each party’s ideology. Using ANES data from 1972–2020, this study shows that partisan bias in perceived party ideology was moderate before 2008 but became dominant thereafter. First, consistent with research on asymmetric ideological clarity, partisans in both parties agreed more on the Republican Party’s ideology than on the Democratic Party’s from 1978 to 2004. Since 2008, however, partisans have shown greater agreement on the opposing party’s ideology than on their own. Second, although the partisan gap in perceived ideological extremity has persisted, it remained moderate before 2000 but has grown steadily since 2008—doubling by 2020. These findings suggest that partisan bias has intensified over time and increasingly overshadows shared perceptions.