Is the rise in campaign contributions the cause of the growing polarity of political views? In this paper, we show that, in standard models of lobbying and electoral competition, a free-rider problem amongst potential contributors leads naturally to a divergence in campaign contributors without any divergence in candidates' policy positions. However, we go on to show that a modest departure from standard assumptions — allowing candidates to directly value campaign contributions (because of "ego rents" or because lax auditing allows them to misappropriate some of these funds) — delivers the ability of campaign contributions to cause policy divergence.