Research on the positions of political parties and party competition regularly assumes that parties are unitary actors with homogeneous policy preferences. While it is clear that elites within one-party may have heterogeneous preferences on specific issues or issue dimensions in reality, measuring such intra-party preference heterogeneity in a way that allows for systemic between-party and international comparison has proved cumbersome. In this contribution, we put forward the largely novel suggestion to use survey data on party candidates for national parliaments for these purposes. Drawing on data from the Comparative Candidates Survey (CCS) from 22 elections in 19 developed democracies that took place between 2005 and 2012, we show that candidates from one party often hold quite heterogeneous issue positions and that the extent of this elite heterogeneity varies significantly across parties and even within parties across different issue dimensions in what appear to be meaningful ways. After discussing the face validity of our measures of intra-party preference heterogeneity and comparing it to related alternatives, we apply it to the question of issue salience. Specifically, we argue that parties will emphasize those issues on which intra-party elite heterogeneity is low. Empirically, we relate our measures of intra-party elite heterogeneity from the CSS to data on issue salience from an expert survey (the Chapel Hill Expert Survey 2010) and from content analysis of party programs (Comparative Manifesto Project). Across different issue dimensions (e.g. economic left-right dimension, European integration, environmental protection, multiculturalism) and the two salience measures, we consistently find that parties attach lower salience to issues over which they are internally divided. While previous research has investigated the link between (expert assessments of) intra-party dissent and issue salience for the dimension of European integration, ours is the first comparative study to examine this link for a range of different issues.
