To win the Republican primary, candidates often move to the right because that is where the political activists and primary voters tend to be. By the same token, to win the Democratic primary, candidates typically move to the left. In a district that is heavily Republican or heavily Democratic, the winner of the dominant party’s primary has no reason to move to the center in the general election. The consequence is the election of Republicans who are more conservative than the average rank-and-file Republican, and Democrats who are more liberal than the average rank-and-file Democrat. It is little wonder that legislative bodies are so polarized — and that many citizens feel that the choices offered to them are so inadequate.