There often exists a supermajority rule that enables the minority party to delay or prevent a vote on a bill. I construct a two-period model consisting of a median voter, self-interested parties, and media outlets. In the model, the majority party has an incentive to misrepresent a desirable policy. I show that the minority party's attempt to prevent a vote (e.g., a filibuster) can be a signal against this misrepresentation, depending on situations. Here, the minority party and the mass media are complementary in creating the signal. Overall, the supermajority rule can be beneficial even for the median voter.