Wither Joementum?

Brendan Nyhan wonders:

What happens to Joe Lieberman if the Democrats take the White House and expand their Senate majority to 56 or 57 seats? Despite his support for McCain, I think Democrats will want his vote on non-war-related issues, so they'll hold their nose and let him keep his seniority in the caucus. Others say he'll be stripped of his seniority, lose his chairmanship of the government affairs committee, and then leave the party to become a Republican.

I have no idea what will happen, but there's very little logic to keeping him in the party. If you had a Democratic Senator who was aggressively campaigning for the GOP presidential nominee, Exhibit A for the case for letting him keep his chairmanship would be "well, he won the Democratic nomination for his seat." But Lieberman didn't win the Democratic nomination. Naturally, under the circumstances he didn't endorse the Democratic candidate for U.S. Senator from Connecticut nor has he endorsed the Democratic candidate for U.S. President. So you've got a guy who doesn't have the Democratic Party nomination, and doesn't support Democratic nominees for federal office. That would seem to make his case for being a Democrat look pretty tenuous.