After Pennsylvania, what next for the Democratic race?

I don't imagine many bets have been placed on Hillary Clinton pulling out of the Democratic race tomorrow. Whether a supporter or not, you've got to admire the former first lady's tenacity - she has the grip of Spiderman on steroids. But a particularly bad result - which at her stage in the game means either a loss or a narrow win - could put her under enormous pressure from senior Democrats to withdraw for the good of the party.

As I explained in my post yesterday, it's not the win but the size of the victory that matters for Clinton in Pennsylvania. She needs to win by some 25 points to have any hope of catching Barack Obama in the popular vote, without which it will be difficult to convince superdelegates to ignore her rival's higher delegate count and pick her as the most electable candidate.

A double-digit victory has been widely touted as the result that would justify her remaining in the race - though surrogates were today suggesting a five or six point win would allow her to claim a success in the face of her rival's much higher spending in the state. While this would still leave her flailing in the mathmatical wilderness, her campaign may well have managed expectations down to a point where this inconvenient fact could be glossed over.

In that case, she would no doubt continue at least until Indiana and North Carolina on May 6th. In both states, she would need to at least hold Obama to a tie or her continued campaign would start to resemble a bad David Lynch movie. With the Illinois senator polling strongly in both states, at present the Obamaite prediction of a May 7 finish to the campaign seems the most likely scenario.

Should her Pennsylvania win be much narrower, however, say two or three points, it would be almost impossible for her to claim any justification for staying in the race. But given Hillary "Rocky" Clinton's almost superhuman ability to keep on getting up off the mat, even that might not be enough to count her out.