Omnibus or not: package bills and single-issue bills in a legislative bargaining game

Legislators sometimes pass unrelated issues in one bill with one vote (omnibus bills), but they often vote separately on different issues as well. In this paper, I consider a model in which the first mover chooses whether to bargain over an omnibus bill or several separate bills. The main difference between the two types of bills is that trade-offs between issues are possible with omnibus bills, but not with separate bills. I use a demandbargaining game (Morelli (1999)) and find that moderate legislators prefer to propose single-issue bills; extreme legislators prefer omnibus bills, if the asymmetry in policy ideal points in the legislature is large enough.