It's obviously clear that the Democratic caucus makes gains in both bravado and the sweet satisfaction of revenge by booting Lieberman from key committee positions -- so that's not the subject of this diary.
As events unfold, it's clear that were this to occur, it's likely that Lieberman would choose to caucus with the republicans.
My question on the Lieberman issue is: what does the GOP caucus gain by adding him as a member? What would he gain by caucusing with the party?
The GOP doesn't isn't gaining (at this point) the single vote they'd need to break a supermajority, and Lieberman would only consistently support their agenda on foreign policy. As Harry Reid put it to CNN:
"Joe Lieberman has done something that I think was improper, wrong, and I'd like if we weren't on television, I'd use a stronger word of describing what he did," Reid told CNN's John King. "But Joe Lieberman votes with me a lot more than a lot of my senators. He didn't support us on military stuff and he didn't support us on Iraq stuff. You look at his record, it's pretty good."
If he was rewarded with minority committee positions, that would certainly invoke the ire of other members of the GOP caucus. In fact, McConnell's staff admitted today that such committee positions are not in the cards, according to Politico.
A Republican Senate aide said Friday morning that there was little McConnell could offer in terms of high-ranking committee slots, which is why Lieberman is resisting overtures from the Republican side.
If Lieberman were to Caucus with the GOP, he doesn't gain votes back home in Connecticut. He narrowly won election as an Independent, after losing the Democratic nomination in a blue state.
There is the chance that the GOP could create a news cycle or two of negative spin against Obama's Democratic party. Yesterday, Boehner railed against the partisanship of the Emmanuel Chief of Staff pick.
It's further likely that punitive action against Lieberman means there's ammo to argue that Obama was disingenuous in espousing bipartisanship, and is now empowering "the ultra liberal wing of the party to purge disloyal politicians." (expect a quote like that in the press release should he get the boot.) In fact, it sounds like this is the case being made by Senator Lieberman.
Lieberman, himself, has no leverage against the Democrats (he's not the magic vote to get to 60 in the Senate). He has no leverage against the GOP (as he's not the magic vote to stop the Democrats from getting 60). He gets no reward for making the move - and could possibly lose his seat in 2012 because of it.
Democratic Senate members (and politics wonks like us) gain a psychological benefit from punishing Lieberman; while the GOP gains a negative news story.
In the end, Harry Reid will do what he's already indicated that he's planned to do:
Reid wants to strip Lieberman of his Homeland Security Committee chairmanship and offer him the chairmanship of a less high-profile committee.
Lieberman will grumble about the action being unacceptable, then he'll accept it.
And in 2012, President Obama will campaign for Lieberman's Democratic rival and he'll be booted out of office for good.