Philadelphia School District officials this fall warned the public that the 2011-12 budget could be grim, with $234 million in stimulus money drying up without funds to replace it.

Now, district officials are staring down a hole of at least $430 million in next year's budget, and the gap could surpass the half-billion mark under the worst-case scenarios, according to government officials briefed on the district's finances.

That's more than 13 percent of this year's $3.2 billion school budget, and without likely sources of revenue to turn to. District chief financial officer Michael Masch is seeking reduction scenarios of 12 percent, 24 percent and 36 percent from each department, according to one source.

Mayor Nutter and Superintendent Arlene Ackerman said in a hastily-called press conference Tuesday night that they did not know the amount of money the district will need to make up in next year's budget. Ackerman called any figures beyond the stimulus money "purely speculative."

"I don't feel comfortable actually discussing this with the press, beyond the $234 million, as we are internally trying to look at a variety of scenarios," Ackerman said.

Nutter and Ackerman called the news conference after The Inquirer began asking questions about the budget.

"We don't want to spend a lot of time speculating," the mayor said, acknowledging that the district, "like every other governmental entity, has some budget challenges."

For two years, the district has relied on federal stimulus money and hefty aid packages from Harrisburg to balance its budget. Of the current $3.2 billion spending plan, $1.68 billion - 55 percent - comes from state aid.

A further $234 million came from non-recurring federal stimulus money. That funding stream is now dry.

And with a Republican governor for the first time in eight years and staunch district ally Rep. Dwight Evans (D-Phila.) out as ranking Democrat in the House Appropriations Committee, the district could be in an excruciating spot.

In October, chief financial officer Masch warned the School Reform Commission - the state-appointed board overseeing district finances - that "some very tough budget decisions" were "inevitable" in the 2011-2012 budget.

Referencing only the evaporating stimulus money at the time, he said his would try to minimize cuts to instruction and other initiatives credited for raising test scores for eight-plus years.

Contact staff writer Kristen Graham at 215-854-5146 or kgraham@phillynews.com.