Street also used the news conference to challenge his Republican opponent, Sam Katz, to a debate about public education, and to strike back at Gov. Ridge for criticizing his call for greater state oversight of the Philadelphia public schools.

He was joined by a campaign supporter, State Sen. Allyson Y. Schwartz (D., Phila.), who echoed Street's opposition to vouchers.

"Those people who advocate for vouchers say that vouchers will provide an element of competition in the provision of public education and therefore overall public education will be improved," Street said.

"Well, I strongly disagree with that proposition and suggest that what vouchers will do is make it possible for a few children who come from fairly well-off families to leave the public school system and maybe go to a private school system, and really not very many of them."

Street cast Katz as a supporter of vouchers, although he said his Republican opponent had yet to make clear his fuller views about the state of the school system.

He invited Katz to debate the issue publicly.

"It is clear that vouchers don't work, and we need to get to the bottom of it, and I need to have a public discussion with my opponent on the whole question of public education," Street said.

A spokesman for Katz, Bob Barnett, said Katz would oblige. Street's offer, Barnett said, comes as a surprise.

"He's been ducking us on a daily basis," Barnett said. "We're happy that he's finally coming out of his shell."

As for vouchers, Katz's position is that the Philadelphia schools are "broken" and policy-makers need to try many different strategies to make improvements, vouchers included, Barnett said.

Ridge, a Republican, who is supporting Katz in the mayor's race, has failed three times to win legislative passage of a voucher program, most recently in June.

Last week, Ridge knocked Street's proposal to give some oversight of the school district to the state authority that now oversees the city's finances.

Ridge faulted Street for what he said was an abandonment of one of the mayor's "prime responsibilities."

Street released a letter yesterday that he has sent to Ridge, reiterating the Rendell administration's longstanding position that the city is not getting enough education money from the state.

"I note with distress that public schools across the state operate in financial distress and even have resorted to suing the state to compel it to fulfill its mandated duty, while the state hoards an accumulated operating surplus of $1 billion. . .," Street wrote.

He cited statistics that state funding for public schools is far below the national average.

Tim Reeves, a spokesman for Ridge, took issue with Street's numbers. If state education funding were thin, "why do we keep winning every one of those lawsuits he mentions?" Reeves said.

He added: "The governor will never abandon the Philadelphia School District and that's why we've increased funding for it every year."

Although Street said he believed vouchers would be destructive - failing to offer poor families enough money to pay for private school tuition - he also suggested he might prove more receptive to the idea if the city were promised enough state money.

That view tracks a position taken by Mayor Rendell, a Street ally. Rendell said in an interview in May that the city might be prepared to drop its opposition to vouchers at least for low-income families in exchange for more state funding. In the same interview, Rendell also suggested expanding state oversight of the city's finances to the school district - the proposal mentioned by Street last week.

"Responsible public officials never say never," Street said yesterday.

"If someone came and said we're going to dedicate $2 billion a year to public education statewide and 10 percent of it will go into a voucher program and there's a way to guarantee that the money will all be available, maybe the senator [Schwartz] and I would have to take a look," he said.