The impact of party polarization on ideological voting

Although ideology is a central factor in models of voting choice, little is known about the factors that explain the variation across elections in the strength of ideological voting. This paper suggests that the role of citizens' left–right orientations increases with party system polarization. It improves on previous studies on this question by avoiding potential sources of bias linked with voters' perceptions of the level of polarization, with rationalization effects, and with the specification of the spatial model of the vote. Based on data from the 1999 European Election Study and from an expert survey on party positions, the results confirm that polarization reinforces ideological voting. However, this effect is mediated by party identification and by political sophistication.