The Median Voter Theory

When there are only two political parties and both parties only aim to maximize their winning probabilities, their best strategies to perfectly match the medium voter's interest. In reality, the situation is definitely much more complicated than the theoretical model; however, winning an election is definitely a priority for almost all political parties. In the US, it might be easy to test how different a political party's policy is from the medium voter's interest, since there are only two major political parties.

If two political parties design their policies based on their expected medium voters' interests (their expected medium voters are not the same), their policies are very close to the true medium voter, the votes they will get will be very close. This comes to my first point. When the votes two parties get are very close, the parties are likely to design their strategies to match the medium voter. Secondly, the two parties may not get their expectations right at first place, so they will correct themselves and get closer and closer to the medium voter. This comes to my second point that when an election is process, if parties are trying to match the medium voter's interests, fewer and fewer voters will be shifting from one party to the other.