Party competition and the structuring of party preferences by the left-right dimension

There is a wide selection of theoretical approaches to explain preferences citizens have for political parties, among them the spatial model of party competition in which voters choose based on proximity in a policy space, such as the left-right dimension. However, it has not ultimately prevailed against its competitors. Thus, a literature has emerged that allows for heterogeneity, asking whose preferences follow this logic and whose do not. However, research on how context affects spatial structuring is still sparse. Therefore, I combine CSES survey data with manifesto data in a sample of established democracies to examine the effects of party competition structure, measured by the “effective” number of parties and the polarization and dimensionality of party positions, on left-right structuration of party preferences in a single model. While I do not find significant context effects with a conventional measure of proximity voting, I propose a different operationalization which shows that while there are systematic effects of the party system, party preferences are mostly quite strongly structured by the left–right dimension.