They are mad at Gephardt because he supports the President on this issue. It's not as much the substance of his position as it is the fact that he made Bush looked good and isolated the anti-war faction within the anti-war party.
In other words, those Dems are mad at Gephardt because he didn't politicize this issue. He went with his conscience -- what he believed to be the right thing to do -- and they're mad at him because it will hurt them politically. And this is the issue they're screaming should not be politicized. Unbelievable. "You have to be the "loyal opposition" whether or not you actually oppose him. That's just amazing.
This is what one observes in politicians when their core value is selfishness.
Ain't life grand!