At both the individual and district levels of analysis there is empirical confirmation of the conditioning effect of party on the association between House members' ideological deviation and constituencies' withdrawal of support for reelection. Democratic incumbents hurt their reelection prospects in general elections by being more liberal than their constituencies prefer; Republican incumbents, by being more conservative. The reverse is true in primaries: Democrats hurt themselves by being too conservative; Republicans, by being too liberal. As incumbents tend to be seriously challenged only in general elections, Democrats can generally take more conservative, and Republicans more liberal, positions than their constituents would prefer with little fear of voter retaliation.