We began with a puzzle in the Senate literature: how do we square findings of party effects (Bargen 2003; Campbell, Cox, and McCubbins 2002; Crespin and Finocchiaro 2008; Den Hartog and Monroe 2008a; Gailmard and Jenkins 2007; Koger 2003; Koger and Fowler 2006) with Senate procedures that seem to preclude party effects? Applications of House-based theories to the Senate (Campbell, Cox, and McCubbins 2002; Chiou and Rothenberg 2003) are supported empirically but are not widely accepted as explanations of Senate behavior (Smith 2007), in large part because they assume, rather than explain, majority agenda-setting power. This assumption flies in the face of decades of literature arguing that individual senators and minority coalitions are powerful agenda-setting actors (Huitt 1961; Lehnen 1967; Matthews 1960; Ripley 1969; Sinclair 1989; Smith 1989).

Our solution to this puzzle centers on the idea that agenda setting is costly – meaning senators must sacrifice scarce resources, such as time, energy, staff, and political chips, to gain final consideration of their proposals. The distinction between getting a proposal to the floor and getting the floor to vote on the proposal is crucial to our take on the Senate – where, unlike the House, much of the significant agenda-setting action happens after legislation is initially proposed on the floor. In the absence of an analog to the House Rules Committee, the Senate majority must battle to get its proposals to the floor, to protect them on the floor, and to move them beyond the floor.