The impact of party-voter congruence on affective polarization: evidence from Belgium

   

Abstract

Ideology drives affective polarization, yet research often overlooks horizontal polarization – emotions toward other voters – and struggles to disentangle ideology from partisanship. This study shifts the focus from vertical to horizontal affective polarization, examining how policy congruence shapes voters' feelings toward in-party and out-party electorates in Belgium's dual multiparty system. Using data from the 2019 federal elections and a Voting Advice Application, we compute a novel measure of party-voter congruence that minimizes partisan signaling. Our findings reveal that policy congruence predicts sympathy toward both in-party and out-party voters, with significant regional differences linked to the presence of a populist radical right competitor. While voters show greater sympathy for their own electorates when policy congruence is high, stronger congruence with one's own party also correlates with reduced sympathy for voters of other parties. Conversely, greater incongruence with other parties reduces sympathy for their electorates and reinforces affective ties with one's own electorate. These results contribute to a nuanced understanding of horizontal affective polarization dynamics in multiparty contexts, underscoring the complex interplay between policy preferences and partisan identities.