Thinking about thereisnospoon's diary up right now, and all of the reasons that Clinton needs to drop out right now for the good of the party, I started thinking about under what conditions that might actually happen.
One factor that we might reasonably expect to sway the Clinton team would be polling that shows a significant shift towards Obama. But something tells me that they are totally committed to seeing Pennsylvania through assuming all other non-polling variables remain constant. Even if he were to be shown ahead in the polls you cant very well drop out after weeks of campaigning and prior to any actual vote taken.
So what might sway them?
I think the most obvious thing would be a huge number of superdelegates (75-125) piling on all at once over the next week or two, which at this point is unlikely to happen. Most of the non-committed supers at this point are very likely going to wait it out and go with the winner. This is either because they have no clear preference or, more likely, because they dont want to be behind a loser. Or, for those who are Obama supporters, we can assume they may have some reason, loyalty etc, for which they do not want to piss off the Clintons.
So the only possible way I see out of this situation quickly enough for democrats to take full advantage of our commanding position going into the election this year is for the remaining power pol's in the democratic party to make a joint endorsement of Barack for the good of the party.
This group most obviously includes John Edwards, Al Gore, Nancy Pelosi and Harry Reid. I dont think this is likely to happen or easy to achieve, but I suggest that the netroots spearhead a movement to pressure these and other important/influential superdelegates to look after the longterm (and even short term) interests of the party now. (Howard Dean, as head of the DNC, may be out of the question, but I think we can guess who he's rooting for).
So John, Al, Nancy and Harry: lets take full advantage of the situation and not, once again, find some way to snatch defeat from the jaws of victory. Lets crush the republicans this fall: endorse Obama for the good of the party. He is the inevitable nominee as it is. Its all a matter of when that is settled.