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 …