Except congress is not unpopular.
Yeah, the democrats are pissed that he tried to undercut their candidate. And what the does he expect? They're not going to give power to him anymore than their going to give power to any Republican. That would be foolish.
Committee Assignments are power and Committee chairs are even more power. Why on earth would the Democrats give power to someone that doesn't support them? That doesn't make any sense. They know he's going to have to vote very liberally or his cons uents are going to vote him out.
No one is advocating Lieberman not stand by what he believes. But when that doesn't benefit the Democrats don't expect them to empower him out of some form of goodwill. They're in there to get things done, not make friends.