Interest groups are introduced in a spatial model of electoral competition between two political parties. We show that, by coordinating voting behavior, these interest groups increase the winning set, which is defined as the set of policy platforms for the challenger that will defeat the...

Interest groups are introduced in a spatial model of electoral competition between two political parties. We show that, by coordinating voting behavior, these interest groups increase the winning set, which is defined as the set of policy platforms for the challenger that will defeat the...

We extend the basic model of spatial competition in two directions. First, political parties and voters do not have complete information but behave adaptively. Political parties use polls to search for policy platforms that maximize the probability of winning an election and the voting decision...

We present a dynamic model of endogenous interest group sizes and policymaking. The model integrates 'top-down' (policy) and 'bottom-up' (individual and social-structural) influences on the development of interest groups. Comparative statics results show that the standard assumption of...