  A proposer requires the approval of a veto player to change a status quo.
Preferences are single peaked. Proposer is uncertain about Vetoer's ideal
point. We study Proposer's optimal mechanism without transfers. Vetoer is given
a menu, or a delegation set, to choose from. The optimal delegation set
balances the extent of Proposer's compromise with the risk of a veto. Under
reasonable conditions, "full delegation" is optimal: Vetoer can choose any
action between the status quo and Proposer's ideal action. This outcome largely
nullifies Proposer's bargaining power; Vetoer frequently obtains her ideal
point, and there is Pareto efficiency despite asymmetric information. More
generally, we identify when "interval delegation" is optimal. Optimal interval
delegation can be a Pareto improvement over cheap talk. We derive comparative
statics. Vetoer receives less discretion when preferences are more likely to be
aligned, by contrast to expertise-based delegation. Methodologically, our
analysis handles stochastic mechanisms.
