The budget crisis hanging over the Philadelphia School District is threatening to claim 100 teaching positions next year, officials said yesterday.

The revelation, which came during a School Reform Commission hearing on the district's proposed $2.18 billion operating budget for 2007-08, drew an angry response from the president of the city teachers' union, who accused schools chief Paul Vallas of mismanagement.

"We have more oversized classes than we have ever had," said Ted Kirsch, president of the Philadelphia Federation of Teachers. "We don't need fewer teachers - we don't have enough now."

Vallas said he has proposed to make the teacher reductions through attrition, not layoffs. Those 100 positions were saved last year because the district had the money to fund them despite the fact that they were above their respective schools' teacher allotments based on student enrollment, Vallas said.

He would be able to save the positions again, he said, if the teachers' union allows the district to delay - by about seven months - making a $9.5 million payment to the union's health and welfare fund, which helps cover the cost of members' prescription, dental and long-term disability plans.

"We gave individual schools extra staff last year, a number of them for the first time," Vallas said. "So it would impact them. But, I think the delay in the health and welfare contribution, which really won't impact health and welfare recipients, is a modest request to make."

Kirsch bristled at Vallas' request, even though it came with the promise of paying interest on the delayed money. He said the union just wants its payment on time to cover its bills.

"I don't think our members should subsidize the school district for its mismanagement," Kirsch said. "[Vallas] is the one who went in front of City Council last May and said we have a balanced budget. He lied. He's now trying to make the union look like we're the ones at fault because we won't agree to his scheme."

An additional 150 teacher positions are being cut from next year's budget because of a projected decline in the district's student enrollment - which has plummeted by more than 40,000 students since 1997.

Kirsch said such a reduction hurts students and is not justified because enrollment declines are spread across the city while the loss of teachers targets individual schools.

He said the district's policy of having student-teacher ratios of 33-to-1 for grades 4th through 12th, and 30-to-1 for grades kindergarten through 3rd, is being violated all over the city.

"We have filed hundreds of grievances, and every time we're scheduled for a hiring the school district postpones," Kirsch said.

Reform Commission Chairman James Nevels said he was not yet sure if the 250 fewer teacher positions next year would result in larger class sizes this fall.

"I'm a little bit concerned at seeing those numbers decline," he said. "What we're going to have to do is see where this is occurring."

"There are schools that think, 'Oh, my God, we keep getting hammered! But they keep having fewer students," said Wayne Harris, the district's budget director.

During the hearing, Vallas said that if the district fails to get $27.6 million in extra funding from the city, deeper cuts would have to be made to his budget proposal.

Those cuts include $10 million in desegregation funds to schools, and losing more teachers through a process called leveling to save about $15 million. Leveling involves shifting teachers in the fall based on enrollment.

Vallas also said that the number of school nurses and counselors would be budgeted at the state-mandated level, meaning there would be fewer of them.