On the same conference call with reporters Tom mentioned below, chief Clinton strategist Geoff Garin tried to downplay the victory margin for tomorrow's Pennsylvania primary. Following a reporter's question asking if Clinton needed at least a double-digit victory, Garin responded that that was "ridiculous."

Garin, along with communications director Howard Wolfson and deputy communications director Phil Singer, said Obama's massive Pennsylvania effort has raised the price his campaign will pay should he lose tomorrow.

"[Obama] is looking to knock us out of the race," said Wolfson. "If Sen. Obama can't win a big swing state with that enormous spending advantage, just what will it take for him to win a large swing state?" Wolfson added that the Obama campaign is outspending Clinton three-to-one. "If he does not win it will again raise very serious questions among voters and superdelegates," said Wolfson.

The conference call coincided with the campaign's release of its "closing argument" ad for Pennsylvania. The view (watch here) blasts Obama for "complaining" about last week's Philadelphia debate, during which Obama fielded tough questions about Jeremiah Wright and William Ayers. "Harry Truman said it best, if you can't stand the heat, get out of the kitchen. Who do you think has what it takes," says the narrator.

Garin argued that to win Pennsylvania, a candidate has to win the "blue-collar and middle-income voters [who] are the heart-and-soul of the Democratic Party."

Responding to the ad, Obama campaign spokesman Bill Burton said, "We already have a President who plays the politics of fear, and we don't need another."