Joe Lieberman didn't campaign for John McCain in 2008 because he's a selfish, whiny, unprincipled back-stabber. According to the new book Game Change, he did it because the Democrats hurt his oh-so-tender feelings:
McCain phoned Lieberman after their Thanksgiving 2007 visit to Iraq.
New Hampshire is going to be everything for me, he said. And there's a lot of independents who are going to vote in the primary. I want to ask if you'd think about giving me your support. If you can't, I'll understand. You're in enough trouble with your party already, but I know it would help me out a lot.
Give me a couple of days to think it over, Lieberman replied. It's a big step, but you know how I feel about you. We've been through a lot together and particularly on the war.
...
On the other hand, not a single Democratic candidate had asked for Lieberman's endorsement, not even his fellow Connecticut senator, Chris Dodd.
For all the distance between him and his party, Lieberman still found that level of ostracism surprising - and painful, very painful.
Gee. Can't imagine why Lieberman would feel so ostracized by his party. Maybe it's because he ran against his party's nominee for the Senate in 2006. Maybe it's because he gave big ol' smooches to President Dubya. Maybe it's because he warned that a Democratic supermajority would be bad for America.
Or maybe it's because he is, and always has been, all about Joe Lieberman.