We examine the role of incumbent fundraising in deterring strong challengers. We construct a signaling model in which incumbents can use fundraising strategically to ward off quality challengers. We show, however, that only under very limited circumstances will there be an observable relationship between fundraising and challenger quality. Therefore, previous empirical tests for deterrence have systematically underestimated the effects of fundraising in decreasing electoral competition. Our analysis also suggests that by making fundraising easily observable, Federal Election Commission regulations may encourage candidates to overinvest time and resources accumulating large war chests instead of governing.