It’s a sore subject, apparently.

Sen. John McCain doesn’t want to talk about the presidential campaign, and he certainly doesn’t want to discuss Sarah Palin…

During a GOP-senators retreat this week at the Library of Congress, McCain told his colleagues that Republicans need to reach out more to diverse groups, rather than just relying on Christian conservatives, if they want to regain majority status, according to sources who attended the event.

“[McCain] talked about the lessons he learned on the campaign trial, and the ‘discussion’ he had with the American public and what he learned from it,” said one GOP insider.

But the man who once called the media his “base” has not done TV or press interviews lately, and he won’t do so for at least several more weeks, according to his aides. He especially wants to avoid discussions about his relationship with Palin, whose nomination as McCain’s running mate was either the best or worst thing that happened to his campaign, depending on who you talk to.

What’s eating him, specifically? Does he feel overshadowed? Bored with answering questions about the backbiting? Reluctant to get dragged into her war with the media? Just had enough of the whole “hockey mom” shtick to last a lifetime? You can run but you can’t hide, Maverick! Eventually he’ll be holding a presser about some bill on the floor and the question will come: “Senator, what do you think of Governor Palin’s statement that she’s had an ‘awakening’ on immigration and now opposes a path to citizenship for illegals?” And then all the bile’s going to come pouring out. Followed by him endorsing Tim Pawlenty in 2012, natch.

Also mentioned at the Senate retreat this week: A lecture about “tone” on immigration. Of course.