This is the result of the fine art of modern congressional redistricting: Red districts are safely red, blue districts safely blue. There is a reason House members don’t see much need to compromise with the other party.

Not only are House members coming from reliably partisan districts, many are winning in landslides. In this fall’s election, 125 House members—42 Republicans and 83 Democrats—won their districts with 70% or more of the vote.

When more than a quarter of House members win so overwhelmingly, in districts that are so safe for them, they are inclined to think they are the ones coming to Washington with a mandate to do things their way, regardless of the national election’s rhetoric or outcome.

The situation is similar in the Senate. There will be 45 Republican senators in the new Congress. Only 10 of them come from states President Obama won. There will be 55 Democrats and independents who caucus with Democrats. Just 11 of them come from states Mr. Romney won.

So, roughly four of five senators come from states where the outcome of the presidential race might be interpreted as a reason for them to stay planted in a partisan corner.