fireball - how much damage do you really think it is doing to Obama with Hillary still in the race and slinging?
I think playing the thing out does little damage if things continue like they did today. Today, before the Edwards announcement, the big political story was Hillary Clinton's new tone, which included defending Obama against a McCain attack and encouraging all her supporters to vote for the eventual Democratic nominee. If she's campaigning with that sort of tone, she can stay in through June 3 without doing any damage.
Would have been nice to hear it a week ago, of course.