Cheesesteak stalemate?

Senators Hillary Clinton and Barack Obama on Tuesday will continue their interminable struggle for the Democratic Party's presidential nomination in Pennsylvania -- home of the 'cheesesteak primary'. 

The state is Clinton's home turf: her father was born there, most of the political establishment backs her, it is a closed primary that excludes Obama's supporters outside the Democratic party, and it is dominated the by down-and-out, blue-collar Democrats who are her core supporters.  She will certainly win.  Only the margin of her victory is in doubt -- but therein lies the key to the remainder of the campaign:

• Clinton needs to triumph by 15-20 percentage points.  A win that big would cement doubts in the minds of Democratic National Convention superdelegates about Obama's 'electability' against the presumptive Republican nominee, Senator John McCain.  Clinton could make a compelling case that Obama's support among working-class whites had been irreparably damaged by the inflammatory remarks of his pastor, and a perception that the Illinois senator is 'elitist'. 
• A Clinton win by approximately ten percentage points would be meaningless.  Her campaign and sections of the US media would describe it as a major victory, but it would not impress the superdelegates, and would make only a small dent in Obama's delegate advantage, which currently stands at over 130 convention delegates. Obama would become the presumptive nominee after the final state primaries are held in early June.
• If Clinton wins by less than seven points, her campaign will be all but finished.  It would be a major moral victory for the Obama campaign in a state where he has few strengths, and might signal that he had begun to make inroads into Clinton's support.  Superdelegates would flock to his banner, perhaps allowing him to wrap up the nomination by mid-May.

The most likely outcome is a solid Clinton victory, well short of the blowout she needs.  A battered, bruised and somewhat tarnished Obama should eventually take the Democratic prize.