The tentative budget agreement reached early this week relies on one-time fixes, including the transfer of money from various funds, that will be not be available next year, Republican and Democrats in the Senate said.

What's more, $40 million that was supposed to be this year's contribution to the state's reserve account, called the Rainy Day fund, is now being used to cover this year's spending.

Paul Dlugolecki, a senior Democratic aide to the Senate Appropriations Committee, said he and others expect such a $1 billion deficit could require a tax increase.

"If this economy continues its downturn, we could easily get up that high," Dlugolecki said. "Two billion is not out of the question."

Sen. Vincent J. Fumo (D., Phila.), who is key in crafting the state budget, believes that projection is a worst-case scenario.

His spokesman Gary Tuma said Fumo thinks the economic recession will "bottom out," and that revenue will pick up by the third quarter of the fiscal year. In that case, the $750 million in the Rainy Day fund would be enough to deal with the reduced revenue collections.

"Could the worse-case prediction be correct? Sure," Tuma said in an e-mail. ". . . But if it is correct, and the problem is of a magnitude that is beyond the size of the Rainy Day Fund, then there is not much that could be done in this budget anyway."

Sen. Gib Armstrong (R., Lancaster), the chairman of the Appropriations Committee, said he expected the state to finish the fiscal year with a deficit between $800 million and $1.2 billion. If that happens, Armstrong said the state could fall back on a number of solutions, including hiring freezes and tapping into the Rainy Day Fund.

Michael Masch, Gov. Rendell's budget secretary, said last night that the dire forecast of a billion-dollar hole was "extreme" and on the "pessimistic end of the spectrum."

The administration expects stagnant growth for the first half of the fiscal year that started earlier this week, but predicts that the economy will rebound from there.

"The budget we are about to adopt puts Pennsylvania in a very strong position to weather whatever comes next with the national economy," Masch said.

The latest twist in what has turned into a labored budget process this year came as legislative staff continued yesterday to hammer out the details of the budget deal Rendell and top lawmakers negotiated in the wee hours this past Monday morning.

By late into the evening, many details on the proposed $28.2 billion budget that increases spending by 3.8 percent over last year were still sketchy. And several rank-and-file lawmakers complained throughout the day that they, too, did not have enough information about the spending plan to make an informed vote.

Earlier in the week, officials gave a brief outline of the proposed budget. They said it contains $274 million in new education funding, and more than $2 billion in borrowing for bridge repair and water and sewer projects. Beyond that, it trimmed $545 million out of other departmental items.

It also creates a $650 million renewable/alternative energy development fund, of which $500 million would be borrowed.

Rendell said Wednesday that he did not want to release any additional information on the budget that might upset the delicate final negotiations.

"From the time a deal is made until the time the budget is submitted to me to sign, there are many hiccups, and bubbling controversy could pop up," Rendell told reporters.