Republicans are vowing to learn from their mistakes in Senate races in 2010 and ’12. Most of them are convinced they would have 50 seats, not the 45 this election left them with, had they run better candidates. Senate Republicans say they are therefore going to get more involved in primary campaigns.

In the process, they will find that candidate selection isn’t easy to fix – and is the least of their problems.

In 2010, the Senate Republicans’ campaign arm, run by Sen. John Cornyn of Texas, was taken by surprise by the tea party surge in the primaries. Cornyn backed losing candidates in Alaska, Connecticut, Delaware, Florida and Pennsylvania. Two of the politicians he supported ended up leaving the Republican Party because they had so little support within it.