The American Federation of State, County and Municipal Employees cheered the support of Libous, the deputy majority leader, and Silver as well as Comptroller Thomas DiNapoli Tuesday as the union began airing a radio ad to blunt Cuomo's popular support.

The ad says politicians are trying to "stick it" to working people instead of making Wall Street and big corporations pay their fair share.

Cuomo says taxpayers can't afford the generous pensions for future workers funded by state and local governments.

Cuomo's plan for future workers offers an optional 401k-like plan and cuts benefits compared to the guaranteed, traditional pensions assured for current workers and retirees under the state constitution. Supporting him are local government officials, including New York City Mayor Michael Bloomberg. They say their employer contributions will bankrupt their towns, villages, cities and counties. But first, they say rising pension costs will force layoffs and sap services including street repair and parks.

Cuomo seeks a far less costly and less generous "Tier VI" for new hires that would end what he calls abuses like loading up on overtime pay in the last years of service to pad pension benefits. Cuomo also wants an optional and portable 401k-like retirement plan that would reduce government employer costs while shifting more of a burden of saving and risk on the employee.

Comptroller Thomas DiNapoli, the pension funds trustee, drew cheers in his opposition to the 401k option, which he said isn't enough. He said 401k retirements plans were created as a supplement to a traditional pension, not a substitute. The Democrat also said Cuomo's proposal would offer governments minimal savings, and a more thoughtful debate is needed with union leaders to develop a better plan for governments and future workers.

"It is one of the seminal clashes of this budget and of my administration," Cuomo told reporters last month. "The question is, does this body, does this government, does this Legislature perpetuate a pension system that is on the verge of bankrupting the state … or does the Legislature respond to the needs of the people?"

AFSCME protesters sometimes spoke as if Cuomo was seeking to slash their pension benefits, which are guaranteed in the state constitution, rather those of than future hires.

"When I went to work, we knew you were going to be paid less, but we also knew that there would be a decent and guaranteed pension at the end," said Gary Tavormina, a retired prison lieutenant who said he survived two riots in 33 years at work.

Silver urged Cuomo to negotiate a better bill with unions, as previous tiers of the pension system were done.

Cuomo has said this is a legislative issue, not part of collective bargaining. But Cuomo spokesman Josh Vlasto said the Democrat is talking to unions, if not negotiating.

E.J. McMahon of the fiscally conservative Manhattan Institute calls the pension fight "a huge test for Cuomo."

"If this is 'worked out' with unions, the result is unlikely to be a true reform, no matter what all the parties claim in the end," McMahon said.