At the mayoral forum held by the Center City District yesterday, something happened that hadn't happened in any of the dozens of forums to date:

An offer of a million-dollar bet.

The proposition was made by candidate Chaka Fattah to candidate Tom Knox whose personal wealth, and his willingness to spend it on his own campaign, has been central to the race.

While the wager wasn't consummated, it did provide some needed pizzazz to yet another gathering of Philadelphia's Democratic mayoral contenders.

Fattah was laying out what he describes as the centerpiece of his campaign: his plan to lease Philadelphia International Airport to a private operator and use the proceeds to fund an ambitious anti-poverty initiative.

Knox questioned the feasibility and legality of the idea, concluding, "We can't do it."

"Would you like to bet a million on it?" Fattah shot back.

Knox pointed out that leasing the airport is not permitted by federal law, which allows only one U.S. hub airport to be privatized. Chicago Midway has taken that slot.

"I promise you that we're going to be able to do it," said Fattah, who has noted that legislation to allow more airport-privatization is moving through Congress.

Fattah urged Knox to go ahead with the bet, saying that the winner would give the money to CORE Philly, a program he created to help needy young Philadelphians go to college.

"You know, I have a million," Knox said, underlining the fact that it was not clear how Fattah would come up with his part of the wager.

At this point, host Paul Levy of the Center City District asked the only other candidate attending the forum, Michael Nutter, if he felt the need to say anything.

"No," said Nutter, "it's just getting good."

When the betting talk died down, Nutter joined Knox in disputing the notion inherent in Fattah's plan - that a single initiative can make a big dent in the widespread poverty and lack of educational achievement that darken the city's long-term prospects.

"Let's be very clear," Nutter said. "There is no one idea here in Philadelphia about how to do anything. . . . I have 10 different ideas that create opportunity."

After the forum was over, Fattah repeated his claim that leasing the airport - assuming that the legislation passes in Congress - is something that could be done by the end of the first year of his administration.

"People talk like this is such a strange idea, but there are lots of examples of transactions to lease public assets for the public's benefit," Fattah said.

Knox made it clear that there had never been any possibility of the bet's actually being made - "I don't bet money on anything" - but seemed to tone down his criticism of the idea of the airport lease.

Asked if he would oppose a lease if Congress expanded the airport-privatization program, he said he was not sure.

During and after the forum, Fattah sought to clarify comments he made to an urban-design forum last week that he was "interested in rebuilding the lives of people and not just the skyline."

As mayor, Fattah said, he would be a friend to Center City and an advocate of city planning, though his priority would be "educational attainment and intervening in generational poverty."

Said Fattah, "We can do both."

Contact senior writer Larry Eichel at 215-854-2415 or leichel@phillynews.com.