Lieberman would posture, express "serious concerns", maybe even crack a tear or two, but he'd still vote for Democratic leadership. Regular Stockholm syndrome.
That's my prediction.
Bingo. Loserman will give a speech complaining Harry Reid is too partisan and needs to work with the President, then Loserman will "reluntantly" cast the tie-breaking vote to deliver the Senate to the Dems.
Dems will then act like they did when Dachle took power and treat the GOP "minority party" like sub-humans.
The Loserman supporters on FR will pop the champaign and tell us how much better it is that Conn.'s senator is "only" 90% liberal instead of 95% liberal, so it's a "symbolic victory" over Daily Kos.