"If you've been in Washington too long like he has the world gets turned upside down -- your opinions become firm but your principles become flexible," said Illinois Rep. Rahm Emanuel, the architect of the 2006 Democratic takeback of the House, speaking of Lieberman.
"Hey, I'll for having friendships regardless of party labels, but I'm also for my principles," he added. "And Joe has fundamental differences with McCain on the environment, a woman's right to choose... What you can't do anymore is roll your eyes and say, 'Oh, that's just Joe.' Lieberman knows what he's doing and there are consequences."
Endorsing McCain was one thing, Emanuel said, but accepting a hero's welcome in the belly of the GOP beast is "something different."
Democrats stopped just short of slapping the traitor tag on Lieberman, who was forced to run as an independent after being bested in the 2006 Democratic primary by anti-war candidate Ned Lamont.
"Ned Lamont was right," quipped Howard Wolfson, Hillary Clinton's former communications director and top strategist.
"Joe will be very happy in the Republican party where the dominant ethic is selfishness -- He's just like Barry Bonds when it comes to selfishness," Begala added. "If you're hanging off the edge of a cliff by a rope, you don't want to look up and see Joe Lieberman."
Yet despite widespread disdain for Lieberman's decision to endorse McCain -- Senate Democrats have been reluctant to strip Lieberman of his position as chairman of the homeland security committee or even say anything too nasty about him in public. The Obama campaign declined comment.
James Carville, Begala's compadre on the 1992 Clinton campaign, say's he not "shocked or angry" -- and was more upset at Lieberman for his oversight of the Hurricane Katrina cleanup first as ranking member of the committee, then as its head.
"I just wish he had been as passionate about FEMA and the Army Corps of Engineers as he is about John McCain," said the Lousiana native, speaking from New Orleans. "Hopefully he'll tell the convention wat a great job he did on overseeing [former FEMA cheif] Michael Brown."
Still, Carville ruefully admitted there was nothing Democrats could do to punish Lieberman without huge wins in November that render Lieberman less relevant.
"They are being smart, they can't tuch him yet, It's just arithmetic, buy a calculator," he added.
"Everybody's pissed at him," said one staffer for a top Senate Democrat, "but we need him."