This paper investigates the role of campaign advertising and the opportunity of legal restrictions on it. An electoral race is modelled as a signalling game with three classes of players: many voters, two candidates, and one interest group. The group has non-verifiable insider information on the candidates' quality and, on the basis of this information, offers a contribution to each candidate in exchange for a favourable policy position. Candidates spend the contributions they receive on non-directly informative advertising. This paper shows that: (1) a separating equilibrium exists in which the group contributes to a candidate only if the insider information about that candidate is positive; (2) although voters are fully rational, a ban on campaign advertising can be welfare-improving; and (3) split contributions may arise in equilibrium (and, if they arise too often, they are detrimental to voters). Copyright 2002, Wiley-Blackwell.
