Candidates competing for political office give promises to voters. There are no legal restraints preventing incumbents from breaking their electoral promises. This paper models campaign promises as pure cheap talk and asks why is it influential. We propose that a candidate's campaign promises are a partially revealing signal of her policy preference type. The incumbent's policy choice is yet another signal of her type. Policy choice is a costly signal (unlike campaign promises). The incumbent keeps her electoral promises in order to preserve ambiguity about her type, which is necessary to assemble a winning majority for reelection. She keeps her promises regardless of information about the efficiency of different public policies which she receives upon taking office. Therefore, campaign promises generate inefficiencies in public policy.