Neither the Clinton nor the Obama campaign would say publicly whether it would comply with Philadelphia's street money customs. But an Obama aide said Thursday that it had never been the campaign's practice to make such payments. Rather, the campaign's focus is to recruit new people drawn to Obama's message, the aide said.

One of his superdelegates puts it this way:

Carol Ann Campbell, a ward leader and Democratic superdelegate who supports Obama, estimated that the amount of street money Obama would need to lay out for election day is $400,000 to $500,000.

"This is a machine city, and ward leaders have to pay their committee people," Campbell said. "Barack Obama's campaign doesn't pay workers, and I guarantee you if they don't put up some money for those street workers, those leaders will most likely take Clinton money. It won't stop him from winning Philadelphia, but he won't come out with the numbers that he needs" to win the state.

Philly isn't the only city with the custom. There's also Chicago, Baltimore, Newark and Los Angeles.

John Kerry paid street money in the hundreds of thousands. So, does Obama look chintzy or should he stick to his principles? And will it cost him in his margin of loss in PA?

Ward leaders say such payments defray expenses such as food and gasoline, and compensate people for a grueling election day.

It is unclear to what extent Obama may suffer at the polls if any part of the city's Democratic apparatus jumps to Clinton.

Obama's strategy in Pennsylvania depends on a strong turnout in the city's black precincts. That way, he can cut into the advantage Clinton has among older and blue-collar voters elsewhere in the state.

Campbell said she could not in good conscience ask people to work for Obama for free. "I'm not going to do that," said Campbell, who heads a coalition of black ward leaders. "There are a lot of poor people here."

Another ward leader puts it this way:

Garry Williams, a ward leader based in north-central Philadelphia, said that he had not heard directly that the Obama campaign was withholding money. But he said payment would be needed. Workers who are in the field for Obama on April 22 will put in days stretching from 12 to 16 hours, he said.

"It's our tradition," Williams said. "You don't come to someone's house and change the rules of someone's house. That's just respect."