Why do some parties and interest groups establish long-term relationships whereas others only seek input and attempt to influence policy on an ad-hoc basis? And how can we account for the intensity of structured relational ties between these two types of political organizations? Even though parties and interest groups may share long-term policy goals, and thousands of lobbyists approach political parties and their representatives in capitals around the world every day, we know surprisingly little about the patterns of structured interaction and collaboration in policy-making between particular parties and organized interests. In this paper, we draw on resource exchange theory to account for variation in the strength of relational ties between individual parties and interest groups today. We hypothesize that ideological/issue proximity paves the way for relational ties, but that mutual provision of resources (like votes, donations or access to government) is needed to effectively explain the extent to which parties and groups choose to establish or maintain relational ties. Using data from a novel organizational survey of parties and interest groups conducted simultaneously in seven Western democracies we are able to test these hypotheses but also examine how institutional factors may limit the actors’ ability to use their specific resources to establish relational ties to each other. Our results will have important implications for the understanding of political parties, interest groups and political representation more generally.
