Davis said liberals have judged Lieberman by the company he keeps. ``He took his friends where they came,'' Davis said. ``That came with a price.''

And Lieberman's Democratic voting record also is overshadowed by overtly helping Republicans or criticizing Democratic leaders.

After Reid remarked in April that the war in Iraq had been lost, Lieberman said he not only disagreed, but also that ``Sen. Reid's statement is not based on military facts on the ground in Iraq and does not advance our cause there.''

What has rankled the anti-war activists even more, though, was Lieberman's active effort to defeat Maine Democrat Tom Allen's U.S. Senate bid.

Lieberman in June co-hosted with Sen. Arlen Specter, R-Pa., a $3,000-per-person fundraiser for Sen. Susan M. Collins, R-Maine, a longtime friend who campaigned for Lieberman in 2006.

Officials at MoveOn.org were so angry they organized an Internet effort to raise money to counter Lieberman's action and wound up raising at least three times as much as the $115,000 the event brought in.

Collins, though, was thrilled at Lieberman's work. ``It was the most successful Washington fundraiser I ever had,'' she said. ``And people said it was refreshing to have the bipartisan atmosphere.''

Lieberman offered no apology.

``Susan Collins is a great senator and deserves to be re-elected,'' he said. ``Why wouldn't I co-host a fundraiser for her? If I'm for her, I'm going to be for her. I'm not going to play the political game.''

He said he criticized Reid publicly because of the leader's clout.

``I try not to get into personal attacks,'' Lieberman said. ``But in some ways the war is being fought here at home, too. If leader Reid convinces people the war is lost, support will grow for that position.''

Some Lieberman friends privately thought he went too far in the Reid and Collins cases. Longtime Lieberman critics were less shy about expressing their anger.

``He had already made a point of betraying his voters and his caucus,'' said Eli Pariser, executive director of MoveOn.org. ``And he goes out of his way to endorse the White House talking points.''

But trying to beat a Democrat, Pariser said, ``was drastic.''

Democratic colleagues say they remain comfortable with Lieberman, and understand, as Sen. Ben Nelson, D-Neb., put it, ``his view on the war is a matter of conscience.''

A more cynical view is that Democrats have to be nice to him because his defection would cost them the majority.

``Democrats in the Senate generally know him and like him, but they also have no choice,'' said Donald Greenberg, associate professor of politics at Fairfield University. ``They have to massage his ego.''

Pursuing Bipartisanship

Lieberman has succeeded in applying at least a veneer of bipartisanship to the Senate.

In the Senate homeland security committee, of which Lieberman is chairman, members do not sit in the traditional way, with Democrats on one side and Republicans on the other; they alternate, with a Democrat seated next to a Republican next to a Democrat, and so on.