Do the Advantages of Incumbency Advantage Incumbents?

We develop a model that calls into question whether some key sources of incumbency advantage frequently cited in the empirical and theoretical literature are, in fact, beneficial to incumbents. Our results show that increases in ostensible benefits of incumbency associated with these sources make it difficult for voters to differentiate incumbents of higher and lower quality. While this leads to an improvement in the electoral prospects of lower-quality incumbents, it is harmful to those of higher quality. Whether the net electoral consequence for high-quality incumbents is positive or negative depends on whether an ostensible source of incumbency advantage affects candidate entry and exit decisions directly or indirectly, as mediated through voters ’ choices. Our findings suggest, further, that fundamental tensions may exist between different sources of incumbency advantage, and point to obstacles to disaggregating the sources of incumbency advantage empirically. “Incumbency advantage ” typically refers to the electoral margin a candidate enjoys on ac-count of her status as an incumbent running for reelection. An extensive literature in American politics beginning in the 1960s and 1970s has documented the existence of such a margin