Partisan Conformity, Social Identity, and the Formation of Policy Preferences

While much is known about the influence of partisan elites on mass opinion, relatively little is known about peer-to-peer influence within parties. We test the impact of messages signaling political parties' issue stances on citizens' own professed policy preferences, comparing the influence of party elites to that of co-partisan peers. Using an online experiment conducted with a quasi-representative sample of Americans, we demonstrate across two policy domains (education and international trade) that the opinions of co-partisan peers are just as influential on citizens' policy preferences as the opinions of party elites. Further, the mechanisms underlying elite and peer influence appear to differ, with conformity to peers - but not elites - driven almost exclusively by strength of social identification with the party.