Bogus email publisher Zengerle's article on Joe's woes is actually quite good. Among other things we learn that Joe's very angry. According to the Official Handbook of Punditry, anger is a terribly bad thing which only insane unhinged crazy bloggers have, and so everything he says should be dismissed accordingly.
Ezra chimes in on what motivates Lieberman supporters - a sense of entitlement and privilege. I think he's got most of it, but there's one more little important bit. The thing is that Joe has done Everything Right according to the Beltway Geniuses, at least before Joe Klein discovered he was for populism after he was against it. He scolded the nasty Clenis, he scolds other Democrats, he supported the Iraq war, he goes on the Sunday teevee shows all the time. He's embraced the "I'm a Democrat but I'm not like those other nasty Democrats" schtick which all cool kids know is the only way to be a cool Democrat. They object to the challenge to Lieberman because they see it as a challenge to themselves and their view of how things should be done.
...and Bill Kristol hearts Joe. So, on one side we have Marshall Wittman and Bill Kristol...