Optimal supermajority requirements in a two-party system

Legislative governance in the United States is characterized by a system of checks and balances. On the one hand, agenda-setting power is concentrated. The majority party has significant control over the agenda. Such power is tempered by supermajority requirements (such as the 60-vote requirement for invoking cloture), bicameralism, and the presidential veto. I develop a theory of legislative outcomes which incorporates supermajority requirements. I argue that supermajority requirements can, in fact, serve an important purpose in balancing concentrated agenda-setting power. I find that substantial supermajority requirements are optimal for legislation, if the aim is to enact policies preferred by the median voter.