Clark's entry might help Dean?

Matt Singer, over on Not Geniuses, has an interesting post in which he tries to talk down some of the assumptions Clark supporters have about what will happen if and when Clark enters the race. He covers some of the same ground I have (but does it better) plus brings up some points that I had not yet considered. Specifically, the question of support from establishment Democrats. There seems to be the assumption among some Clark supporters that if he were to enter he would almost immediately get the lions share of the establishment endorsements. As Matt points out, a lot of those establishment Dems have already picked their candidates (Kerry, Gephardt, Lieberman, even a few for Dean). Are they likely to simply drop their guys the minute Clark announces? I think not. Clark's entry, far from solidifying the "Anybody But Dean" movement, might actually fracture it even more and make it that much easier for Dean to win.