Mass opposition to Europe may stem from mainstream as well as formally Euroskeptic parties. Large parties in the member states of the European Union (EU) tend to combine support for Europe with a high level of intra-party dissent over the issue. Thus, these parties provide heterogeneous yet potentially influential signals about European integration to their supporters. In this paper, we examine the effect of intra-party dissent on the opinion of party supporters. Our estimation of this relationship explicitly addresses the issues of endogeneity, omitted variables, and measurement problems endemic to the empirical study of elite effects on mass opinion. Specifically, we use variation in the centralization of candidate selection rules as an instrumental variable for intra-party dissent. We find substantial evidence that intra-party dissent does indeed increase variation in support for integration among party supporters. With common levels of intra-party dissent, even pro-EU parties can cause a substantial portion of their supporters to adopt anti-EU opinions.
