Chris Matthews just made fun of me on "Hardball"--it wouldn't be the first time!--for saying that we won't know how dire, how hopeless, Sen. Hillary Clinton's situation is until later tonight. We'll know it when we see it, I said. What are you, the Supreme Court? Chris asked with justifiable glee.

But the fact is, after all of the money and message and machinations, the fate of the Clinton campaign rests depends not just on the vote totals or delegates won per se, but on how the whole thing feels by, say, midnight.

It's no longer a question of what Hillary herself thinks-she wants to stay for the duration, a close friend of hers tells me-but whether and when the leaders of the Democratic Party unite, publicly and privately, to tell her to get out if she wants to have a future leadership role in her own party.

As my colleague Jon Alter convincing showed today-calculator in hand-there is just no way, barring some kind of cataclysmic event, that Clinton can overtake Sen. Barack Obama in pledged delegates. Obama won’t have enough of them to clinch the nomination on that basis alone, but she can’t catch him.

So Clinton's only chance rests with winning over party elders, and the 794 superdelegates who are free to vote for whomever they choose regardless of the primary or caucus results in their own state. By my count, about 350 of them remain up for grabs.

But she needs to do more than just eke out a victory or two tonight to make the claim that Obama is somehow unelectable. Instead of having won 11 in a row, he will have won, say, 13 out of the last 15 events. Not exactly a collapse.

Obama almost certainly will win Vermont, the home of Ben and Jerry. So that means Hillary essentially has to sweep the rest to fully forestall a move by party leaders to tell her to quit.

I have spent a good part of the day listening to dueling conference calls from the Clinton and Obama camps. Howard Dean is right in what he just said to Chris on Hardball. So far, the "attacks" are a "tea party" compared with what is to come.

But if Clinton continues to the next stage-if the results tonight allow her to fend off those telling her to quit-the next round is going to be a lot nastier. It's going to get into Obama's South Side Chicago roots; into some of the wilder statements of his longtime minister, Jeremiah Wright; and into the not-so-sly raising of doubts about Obama's religious beliefs.

Does Hillary really want to go there? Maybe not, which is why I think some of her own supporters (and maybe even some of her own campaign aides) would just as soon that this thing end tonight.