Sequential Vote Buying

Abstract

To enact a policy, a leader needs votes from committee members with heterogeneous opposition intensities. She sequentially offers transfers in exchange for votes. The transfers are either promises paid only if the policy passes or paid up front. With transfer promises, a vote costs nearly zero. With up-front payments, a vote can cost significantly more than zero, but the leader is better off with up-front payments. The leader does not necessarily buy the votes of those least opposed. The opposition structure most challenging to the leader involves either a homogeneous committee or a committee with two homogenous groups. Our results provide an explanation for several empirical regularities: lobbying of strongly opposed legislators, the Tullock Paradox and expansion of the whip system in the U.S. House concurrent with ideological homogenization of parties. We also discuss several extensions including private histories and simultaneous offers.