This paper presents a complete information model of competitive lobbying in a majority-rule institution where lobbying consists of support provided to legislators in the form of politically valuable resources. Two lobbyists alternate in recruiting legislators, who have three roles in the institution. First, they act as allies or opponents in deciding whether to consider a lobbyist’s offer. Second, they act as agenda setters in deciding whether to bring a policy alternative to a vote. Third, they vote on the agenda. The equilibria are driven by the stakes of the lobbyists and the constituency costs of legislators. Depending on the stakes and the constituency costs, the equilibria include minimal majorities, supermajorities, and preemptive lobbying. Lobbying focuses on legislators predisposed against the interests of the lobbyist, unless the lobbyist counteracts the other lobbyist. The power in the lobbying relationship rests with the lobbyists when they do not recruit the same legislator and with the legislator when they do.