The looming round of budget cuts appears to have made managers across city government jittery, particularly at the Free Library of Philadelphia, which in a cost-cutting move eliminated Saturday hours at 27 of its 53 branches over the weekend.

The only problem was that Mayor Nutter had not signed off on that slash in service. Once he got word from a reporter that some libraries had been closed Saturday, he ordered them reopened, at least for now.

"This was a unilateral decision made by the library. They did not have the authority to make that decision, so that decision has been reversed," Nutter spokesman Doug Oliver said.

Since Nutter announced last month that the city faced a budget gap of at least $450 million over the next five years, city administrators have been looking for ways to cut costs. Some departments were told to expect cuts as steep as 10 percent.

"When the mayor says we have to hit the spending brakes, people start reacting. There's a sense of instability," said Councilwoman Maria Quiñones-Sanchez, who would rather see tax cuts rolled back than services cut.

Speculation is rampant in city government that the real budget gap is far bigger than the $450 million announced last month, and the list of potential budget victims includes city ice rinks and pools, Town Watch programs, new police hires, and $2 million in extra funding for Fairmount Park.

So far, the administration has refused to address the rumors, insisting that no final decisions have been made. Nutter has said he will not announce the budget casualties until the spending review is finished at the end of the month.

"As the mayor has said from the beginning, we're not going to debate the cuts in public prior to coming to a conclusion," Oliver said.

So library president Siobhan A. Reardon, who did not return a call seeking comment for this article, appears to have jumped the gun. But the library's budget still could be cut, making shorter hours or shuttered branches necessary.

Recreation Department officials recently met for a presentation assessing which recreation centers could be closed or get by with reduced operating hours. For now, cost-cutting measures seemed likely to be leaving vacant positions unfilled, cutting back on part-time jobs and reducing staff at five city ice rinks.

"My theory is, if we reduce anything, we are going to be cutting services to kids at this point. We can't cut anything else," said Michael McCrea, president of the Philadelphia Recreation Advisory Council, which represents nearly 190 volunteer groups.

To McCrea and others, the discussions are uncomfortably similar to those of 2004, when proposed belt-tightening moves included closing or leasing more than 30 recreation centers, and shuttering 20 city pools and several fire stations.

Although unlikely given the upheavals of the national economy, local tax returns might be strong enough for the city to avoid steep cuts.

Compared with last year, city revenue has been soft through the first three months of the fiscal year, which began July 1. But administration budget planners anticipated that and drafted a spending plan based on a small decline in the wage tax. So although wage-tax collections are down compared with last year, they are not down quite as sharply as budgeted.

If that trend continues and other city taxes hold up, the 2008-09 budget gap might not be as big as initially feared.

That's a big assumption, however, in a week when Wall Street continues its self-immolation.

Contact staff writer Patrick Kerkstra at 215-854-2827 or pkerkstra@phillynews.com.

Inquirer staff writer Jeff Shields contributed to this article.