Ulric B. and Evelyn L. Bray Social Sciences Seminar

Abstract: Spatial models of agenda setting are central to the study of legislative politics, yet they typically abstract from the influence of interest groups. To address this gap, I unify the classical one-dimensional agenda setting framework with models of vote buying, starting with one group and extending to two moving sequentially. Anticipating the groups' responses, the agenda setter strategically adjusts proposals to take advantage of support or to preempt opposition. This unification generates a number of insights into interest groups' behavior, and how their influence affects gridlock, coalition size, and policy moderation. Most notably, the model offers a new explanation for supermajority coalitions: rather than arising from competition between vote buyers, supermajorities emerge because the proposer biases policy toward the opposing group to reduce the likelihood of opposition. Contrary to previous theories, coalitions can be larger when there is just a single interest group than when there are two.