By Danny Hakim and Nicholas Confessore

ALBANY — With the downfall of Gov. Eliot Spitzer and an approaching state election that has senators of both parties desperate for support, labor unions are flexing their muscles in the capital to a degree not seen in years.

The unions’ push has set up an early test for Gov. David A. Paterson, a longtime friend of labor who is trying to refashion himself as a cost cutter in the face of the state’s coming fiscal crisis.

The unions want their pensions sweetened and their health benefits set in stone. They want local school districts to continue to increase their budgets without interference from the state, and they want to force some nonprofit groups to pay higher wages.

They have already scored a victory by stripping language out of state law that linked decisions on teachers’ tenure to their students’ performance on standardized tests.

The unions are moving aggressively on their legislative agenda in part because Mr. Paterson is viewed as a relatively weak governor, whereas Mr. Spitzer battled some of the most powerful unions in the state. In fact, there is no effective counterweight to the unions’ clout, given the limited influence of the state’s business lobby and how close the state’s top Republican, Senator Joseph L. Bruno, is to labor leaders.

“Labor is in a good place,” said Richard C. Iannuzzi, president of New York State United Teachers, one of the most powerful interest groups in the capital. “The atmosphere in Albany, for a variety of reasons, has been somewhat chaotic and combative, and that’s allowed us to use our ability to be consistent to our advantage,” he added. “It’s an odd place to be, but we’re adding stability to a confusing situation.”

The governor, a Harlem Democrat, said in an interview Tuesday that he would resist any increased spending in the weeks ahead. “Everyone is probably going to be mad at me,” he said.

“I understand what labor’s intent is; it’s to fight for the best contracts for workers,” Mr. Paterson added, but said, “Someone has to present fiscal reality to the Legislature, the advocates and a lot of otherwise good causes.”

“I am going to look at these bills very critically,” he said, and added that since the state faces a $21 billion deficit over the next three years, “I am not going to back down.”

Many political observers wonder whether the genial governor will have the strength to deliver on his rhetoric, or whether the Legislature will override him if he tries to veto its acts.

Mr. Paterson sided with the teachers’ union last month in restoring planned budget cuts to primary education and sided with them on tenure as well. He has clashed with them in recent weeks, however, by significantly cutting the state’s higher education budget and restricting the State University of New York’s ability to spend tuition paid by its students.

In part because of the abruptness of his ascendance to the governor’s job, Mr. Paterson has not finished assembling his staff and formulating his agenda. The resulting uncertainty worries fiscal conservatives.

“There’s a real danger that in the current situation there’s a bigger void than usual, and the unions are the 800-pound gorilla who will fill it,” said Edmund J. McMahon, director of the Empire Center for New York State Policy at the Manhattan Institute.

“Their hand is stronger than it’s ever been,” he said, adding, “The Legislature might be more cowed by the unions than they have ever been.”

Fighting the unions could be costly. In 2004, when Mr. Paterson was Senate minority leader, he received roughly $230,000 from unions, either for his own campaign or for those of Senate Democrats; that is a substantial amount for the leader of the minority party to attract.

Unions have long had an outsize influence in New York. Porous laws allow them to put millions of dollars into campaigns. The powerful hospital workers’ union, 1199 S.E.I.U. United Healthcare Workers East, is one of the largest contributors to Senate Republicans, creating a close political alliance that helped them last year when Mr. Spitzer took them on in a bitter budget fight. The union had more than $5 million in campaign expenditures in 2006, according to the state’s Board of Elections.

There are about six weeks remaining in the legislative session, and labor groups are pushing a long list of proposals, some of which could be costly.

The teachers’ union has already outlined its firm opposition to any proposal to put a ceiling on local property tax increases; such a proposal is expected from a special commission due to issue a report next week. The A.F.L.-C.I.O. wants legislation forcing employers to grant paid family leave — an idea Mr. Paterson supports — and to limit nurses’ overtime.

The Civil Service Employees Association is backing a bill that would prohibit municipalities from cutting their retirees’ medical benefits.

Stephen J. Acquario, the executive director of the New York Association of Counties, said the measure would lead to “a collective bargaining quagmire.” Danny Donohue, the president of the union, said it would ensure “that localities live up to their responsibility to retirees.”

There are also perennial efforts to enhance benefits. District Council 37, an umbrella group of municipal unions in New York City, has been backing a bill that would give members a second chance to buy into an early-retirement plan. City officials estimate that the plan would cost them $200 million annually; lawmakers say it would have no cost.

Mayor Michael R. Bloomberg has asked the governor to reject the measure. “If he’s right about the numbers,” Mr. Paterson said, “then we can’t afford to do it.”

Union lobbying has tied up legislation that would reauthorize local industrial development agencies that help finance capital projects by nonprofit groups. More than $2 billion worth of construction projects have been halted by the delay, including new hospitals and schools. Unions want to require recipients of the tax-exempt financing to pay a “prevailing wage” for any jobs created with the aid.

Business groups argue that in economically struggling areas, the wage requirement would deter businesses from seeking the tax breaks.

“Obviously, labor is very strong in Albany,” said Brian T. McMahon, executive director of the New York State Economic Development Council. “But many of their agenda items, we think, have hurt economic development.”