Friends say Hillary won't quit tonight, but she'll "take a few days to think about her next move."

Writes Marc Ambinder. Next move. How exciting!

UPDATE: WaPo reports under the headline "Clinton to Concede Delegate Race When Obama Clinches":

Hillary Rodham Clinton will concede Tuesday night that Barack Obama has the delegates to secure the Democratic nomination, campaign officials said, effectively ending her bid to be the nation's first female president.

Oh, she'll concede that he has the delegates? That is not the same thing as conceding, meaning I agree that you have won. He has the delegates now, but the superdelegates can change their position — as some have already committed to her and then shifted to him. They can recommit to her. It's all in flux until the vote that counts, at the convention.

The former first lady will stop short of formally suspending or ending her race in her speech in New York City.

See? She's staying in.

She will pledge to continue to speak out on issues like health care. But for all intents and purposes, the two senior officials said, the campaign is over.

So the campaign goes on and she will speak out on issues. Then what is new? This may be only a necessary acknowledgment of the reality that Obama will have the necessary votes in his column.

I think she will make every effort to look like what she believes she is: the stronger candidate against McCain. Perhaps she is hoping that the GOP will begin its full-scale attack on Obama and scare the superdelegates back to her side. Obama will be the exposed one, and she'll be waiting in the wings, secure in the knowledge belief that everyone knows she is the better candidate, hoping that the cards play out in her favor.