Coalition Opportunity Structures and Advocacy Coordination in Consensus and Majoritarian Democracies

ABSTRACT Research on advocacy coalitions suggests that belief homophily—the tendency of actors to coordinate based on shared policy beliefs—drives coalition formation. However, coalition opportunity structures, which are shaped by institutional contexts, may influence the extent to which belief homophily matters. We argue that coordination dynamics differ between majoritarian and consensus democracies. While majoritarian systems promote moderate norms of compromise and open decision‐making processes, consensus democracies foster stronger norms of cross‐coalition cooperation. Consequently, belief homophily may be a stronger driver of coordination in majoritarian democracies than in consensus democracies, where broader cooperation is needed to introduce policy change. To test this hypothesis, we use data from climate change policy subsystems in nine countries and apply a multilevel structural equation model to examine coordination patterns. Our results show that the more majoritarian a country's institutions are, the more actors coordinate with like‐minded partners. Additionally, in majoritarian systems, coordination is more likely to involve influential actors, emphasizing power dynamics. Conversely, coordination in consensus democracies is less dependent on belief homophily, and broad‐based cooperation is more prevalent. These results underscore how institutional contexts shape advocacy coalitions and contribute to a comparative understanding of advocacy coordination.