NBC's Chuck Todd has the story:
One of the things that both Dem campaigns are always nervous about is defectors. In particular, Clinton is more vulnerable to this problem since she's the candidate that is trailing. Well, NBC News has learned that a major fundraiser for Hillary Clinton, former Amb. to Chile Gabriel Guerra-Mondragon is leaving the campaign to join up Barack Obama's campaign.Eventually, the writing on the wall will be impossible to ignore for all but the most diehard Clinton supporters. Let's hope it's sooner rather than later.
Among the reasons for Guerra-Mondragon to defect, according to one informed source, was he was uneasy with the tone of the Clinton campaign and was beginning to worry about what this would mean for the general election.
Update: That's in addition to the three superdelegates he's picked up since Pennsylvania. Clinton has picked up one.