If You saw ABC's This Week With George Stephanopoulos a smart, TV-savvy Senator sums up the case against Joe Lieberman:

STEPHANOPOULOS: Senator Lieberman thinks that your approach will strengthen the terrorists and it’s a victory for terrorists. What’s your response?
FEINGOLD: Well, I like Joe Lieberman, but I support Ned Lamont, because Joe is showing with that regrettable statement that he doesn’t get it. He doesn’t get it. The fact is that we were attacked on 9/11 by Al Qaeda and its affiliates and its sympathizers, not by Saddam Hussein. And unfortunately Senator Lieberman has supported the Bush Administration’s disastrous strategic approach of getting us stuck in Iraq instead of focusing on those who attacked us. I mean, look at the places that have been attacked: India, Morocco, Turkey, Afghanistan, Indonesia, Somalia, Spain, Great Britain. What does this have to do with Iraq? And Senator Lieberman is stuck on that point. Ned Lamont and I believe that we should refocus on those who attacked us on 9/11 and not simply try to cover our tracks because this was such a very poor decision in terms of the overall battle against the terrorists who attacked us.
STEPHANOPOULOS: Do you think Senator Lieberman should get out of the race?
FEINGOLD: Well, you know, I think that’s his own decision. It would be better for the Democratic Party, I think it would be better for the people of Connecticut, it would be better for the country if he did it. Not because he hasn’t been a good Senator, not because he isn’t a good man, but this is a critical time. And we have to change course. We have to focus on those that attacked us on 9/11 and get away from this very mistaken policy in Iraq. So it would be helpful if he would do it, but obviously Joe will have to make that decision for himself.
9/11 Commission chairmen Tom Kean and Lee Hamilton inadvertently make the argument against Lieberman as well: the Iraq war has diverted resources and our attention away from the primary focus, which should have been destroying Al Qaeda.