From TPM :

The Politico has just posted a story on Joe Lieberman’s battle to hang on to his plum committee slot, but Politico kind of buries the lede. The real story here is that Lieberman’s aides are now openly threatening Senate leader Harry Reid by saying that Lieberman will stop caucusing with Dems if his chairmanship is revoked:

“Senator Lieberman’s preference is to stay in the caucus, but he’s going to keep all his options open,” a Lieberman aide said. “McConnell has reached out to him and at this stage his position is he wants to remain in the caucus but losing the chairmanship is unacceptable.”