What Happens if Clinton Doesn't Win Big on Tuesday?

If Hillary Clinton won't recognize that Barack Obama will be our nominee and step aside soon, the party leadership—Nancy Pelosi, Harry Reid and Howard Dean—will push the superdelegates to make public endorsements, thus cutting off Clinton's plan to take the fight all the way to the convention:

[T]he decisive movement wouldn't likely come until after the final bouts June 3 in South Dakota and Montana, should the race remain unresolved. That's when Mrs. Pelosi, Senate Majority Leader Harry Reid, Democratic party Chairman Howard Dean and their allies will start rallying superdelegates to decide the contest in favor of the leading candidate, Democrats say. Through a spokesman, Sen. Reid declined to comment.

Sen. Obama leads in pledged delegates won in primaries and caucuses, in the number of states won, and in total popular vote. Sen. Clinton isn't likely to change that, unaligned Democratic strategists say, even with wins in Pennsylvania and others of the nine remaining contests.

The party leaders' aim: To thwart the Clinton campaign's vow to fight all summer long to a final, nationally televised round at the Denver convention, so the party can get on with the battle against the likely Republican candidate, Arizona Sen. John McCain.

Convention fights in past decades -- notably in 1968, 1972 and 1980 -- left deep divisions that contributed to the nominees' losses and hurt lesser candidates on the ballots.

With Democrats protective of the House and Senate majorities just won in 2006, "Do you think for one minute that Nancy Pelosi or Harry Reid will allow this fight to go on and on and on?" says Donna Brazile, an uncommitted superdelegate as an official of the Democratic National Committee, and manager of the 2000 Gore campaign. "There's a group around [Sen. Clinton] that really wants to take the fight to the convention. They don't care about the party. It scares me, and that's what scares a lot of superdelegates."

Clinton supporters vehemently defend their right to fight to the convention if necessary, and deny it would hurt the party.

Dean has said he wants the Superdelegates to state their position no later than July 1st, although recently his urgings have been more insistent.  The general consensus is that Clinton won't make up any ground among delegates unless she beats Obama by 20 points or so.  The pundits appear to have settled upon 10 point or more for the victory to give her momentum.  The polls suggest a more modest margin of victory, most likely around 5 points or so.  

What if Clinton wins by less than 10 points?  Or what if, in a big upset, Obama shocks her and wins Pennsylvania?  Will she finally concede that Obama will be our nominee?  The Obama people aren't making it easy for her to stay in the race; from Marc Ambinder:

Despite pressure from the governor, from the local media, from their own-state campaign, Barack Obama's advisers refused to accept an invitation to debate in North Carolina because they did not want to give Hillary Clinton any excuse to stay in the race beyond Tuesday, assuming she doesn't fare that well. The Obama campaign's gambit paid off: the debate is canceled.