PAUL LOEB: “When Democrats worry about Hillary Clinton’s electability, they focus on her reenergizing a depressed Republican base while demoralizing core Democratic activists, particularly those outraged about the war, and thus maybe lose the election. But there’s a further danger if Hillary’s nominated–that she will win but then split the Democratic Party.” Check out the HuffPo comments. [LATER: DailyKos commenters have a similar take.]

Plus this: “Democrat Hillary Clinton would lose to all major Republican White House candidates, according to a hypothetical election matchup poll Monday, reversing her months of dominance over potential 2008 challengers.” I wouldn’t make too much of that poll — it’s from Zogby — but it comes as another blow to her inevitability-based campaign.

UPDATE: Obama smells blood.

ANOTHER UPDATE: It’s on!