In a revealing article in The Hill, Alexander Bolton reports that Sen. Lieberman hinted on Friday that he would consider leaving the party if he was stripped of his seniority:

Lieberman said he would keep his senior position in the caucus, even though he lost Connecticut’s Democratic primary, and is running against Democratic nominee Ned Lamont, whom the Senate Democratic leadership has endorsed.

“That’s what I’ve been told,” said Lieberman in an interview Friday, before Congress recessed for the election. “Caucuses like to keep as many members as they can, not discourage membership,” implying that leaders risk his defection to the GOP if they strip him of seniority.

Also in the article, Sen. Lautenberg (D-NJ) appears to be angling to regain his seniority - on Lieberman's favorite committee - in the face of Reid's alleged guarantee to Lieberman that he would keep his committee assignments:

But the strongest response is likely to come from Sen. Frank Lautenberg (D-N.J.) who views Lieberman’s independent status as an opportunity to press Democratic leaders to restore seniority he lost four years ago.

If Lautenberg retrieves seniority accrued during 18 years of Senate service before retiring in 2000, he could leapfrog Lieberman to lead the Homeland Security and Governmental Affairs Committee or the Environment and Public Works Committee....

“I will make the case, I will make the case,” said Lautenberg emphatically. “The closer to the election, the better the reminder has to be.”