We explore the foundations of the legislative party cartel, as theorized by Cox and McCubbins (1993, 2005), to determine how majority-party moderates who suffer net policy losses from the majority leadership's use of negative agenda control are kept from defecting from the cartel arrangement. First, we identify formally the group of majority-party members who are net policy losers. We find that those members occupying the initial 30% of the space within the majority-party blockout zone—that space closest to the floor median—are hurt on a pure policy basis by the cartel arrangement. Second, we find that members in this “30% zone” are rewarded disproportionately by majority-party leaders (relative to members in other intervals on the same side of the floor median) via side payments in the form of campaign contributions. In addition, majority-party members within the 30% zone receive side payments commensurate with their particular policy loss.