Some Senate Democrats hold a grudge against Lieberman for his rightward turn and opposition to some of President Barack Obama’s agenda late in his Senate career. Others say even though they respect Lieberman, the job of FBI director should not go to a former politician. And all Democratic senators interviewed for this story said the former Connecticut senator lacks the kind of experience needed for the post.

The 2000 Democratic vice presidential candidate, who later caucused with the party as an independent in the Senate after losing his 2006 Senate primary, has emerged as a front-runner to replace fired FBI Director James Comey. But Lieberman’s nomination likely would produce the most partisan vote for an FBI chief in Senate history. Typically, nominees for the job have been approved unanimously or with token opposition.

“I don’t think there’s going to be much excitement about that from our side of the aisle. Not because we don’t respect Joe Lieberman. But we need a law enforcement professional, not someone who’s run for office before,” said Sen. Claire McCaskill (D-Mo.). “We don’t need anyone who’s put on a red shirt or blue shirt — or who’s campaigned for president.” Lieberman ran for president in 2004.