According to Politico, both Hillary Clinton and Barack Obama have despaired of any outright victory before the Democratic convention in Denver this August. The delegate math doesn’t allow for either to win without the superdelegates, and so the remaining contests will matter more for their symbolism rather than their actual delegate counts, especially for Hillary. Can she frighten enough superdelegates about Obama’s prospects against McCain to get them to support her despite being behind in pledged delegates?

Yes, there will be the usual commercials, speeches and town halls in the remaining states. But the prime audience for the candidates isn’t to be found in Altoona, Evansville or Chapel Hill. The voters will merely be playing a supporting role in a race likely to be decided by the party’s superdelegates.

Clinton’s overarching mission now is to raise doubts about Obama’s viability as a general election candidate with the superdelegates who will ultimately decide the outcome. The primary results, then, are relevant only to the extent they drive—or, for Obama, dispel—that argument.

“We believe that [the Pennsylvania results] will show that Hillary is ready to win, and that Sen. Obama really can’t win the general election,” said Clinton’s chief strategist Mark Penn on a conference call with reporters Thursday.

Penn subsequently modified his analysis to say that losing Pennsylvania would only raise questions about Obama’s ability to win in November. But the point was made nonetheless.

Penn took a lot of heat for his pessimistic analysis over Obama’s general-election chances, and that points up the danger for Democrats over what Jonathan Martin and Mike Allen call World War I-style trench warfare. The two candidates have to lob some bombs at each other in order to make the case for their brokered nominations. That means a higher level of negative campaigning that normally seen in primaries, as both candidates will have to play on the fears of the superdelegates to compel their support.

For instance, Hillary’s argument will be to appeal to the reason the Democrats set aside 20% of their delegate total to superdelegates in the first place. She has to argue that Obama doesn’t have the experience or the background to win a general election, an argument that got a lot more traction after the revelation of Jeremiah Wright’s sermons this week. She also has to hint that the superdelegates should insist that Obama take the VP slot instead. Obama has to emphasize that he won’t ever endorse a brokered Hillary win by being her sidekick, and that the superdelegates could see his core voters — the prized African-American voting bloc — walk out of the convention and away from the Democrats up and down the ticket if he doesn’t get the nomination.

Perhaps the World War I analogy isn’t quite as apt as a game of chicken for an explanation. We already know that Hillary will win most of the big industrial states upcoming in the schedule, and that she’ll trail in delegates but not by as much as she does now. As those numbers get closer, the positions will harden — and the question will be which one blinks first, and whether that happens before Denver or on the convention floor.

Update (AP): The Times notes the trend towards Obama among the superdels. Money quote:

“If we get to the end and Senator Obama has won more states, has more delegates and more popular vote,” said Representative Jason Altmire, Democrat of Pennsylvania, who is undecided, “I would need some sort of rationale for why at that point any superdelegate would go the other way, seeing that the people have spoken.”

Obama’s guaranteed to end up with more delegates and almost certainly more states, so the Glacier’s last gasp is the popular vote. How’s that working out? If she loses that too, all she has left to argue is that she’ll do better in the battleground states than Obama will against McCain. Anyone see the superdels flying in the face of Democratic voters to hand her the nomination on that basis?