By Danny Hakim

ALBANY — The next battleground for the teachers’ union is almost certain to be property taxes.

Last week, a special property tax commission set up by former Gov. Eliot Spitzer and supported by his successor, Gov. David A. Paterson, wrapped up its sixth and final hearing. The commission is due to issue a report by May 22 that will include imposing a ceiling on annual property tax increases by school districts as its signature proposal, though the form of any limit remains to be determined.

“There seems to be a real appetite to do something,” the Nassau County executive and the commission’s chairman, Thomas R. Suozzi, said of the idea of a tax cap. Mr. Suozzi added that he had courted the leaders of the Legislature — Assembly Speaker Sheldon Silver and the Senate majority leader, Joseph L. Bruno — and was encouraged.

But here’s the hitch.

New York State United Teachers, the powerful union that holds considerable clout in Albany, cannot abide a cap or several other steps the commission is considering.

“The process is flawed because it starts with the assumption that a property tax cap is something that we need,” said Richard C. Iannuzzi, the union’s president, above. “When you start with the conclusion that it has to be a cap, you limit the ability to look at things.

“That destroyed the public school system in California, and we’re not going to let that happen in New York.”

Demands for a property tax cap have been growing on Long Island, in other New York City suburbs and upstate as property taxes have become more of a burden.

But the union’s opposition is no small matter. The group is so influential that last month it successfully lobbied to have language excised from state law that linked teacher tenure decisions to the performance of students on standardized tests. Senate Republicans had resisted the move initially but were muscled by the union, whose political support is seen as critical to helping Republicans keep the closely divided State Senate in the November elections.

While a cap would be a districtwide measure, another proposal that is likely to emerge from the commission is a so-called circuit breaker that will limit people’s property tax bills based on their income.

More-controversial ideas that the commission may turn into proposals include a scaled-back pension plan for new teachers and making changes in the Taylor Law, which bars public-sector unions from going on strike but also guarantees pay increases. Specifically, the commission has discussed repealing the Taylor Law’s so-called Triborough Amendment, which locks in incremental pay increases after a public contract expires and before a new one is agreed upon.

“Some of the things being discussed are an attack on teachers, when you talk about the Triborough and a new tier in the retirement system,” Mr. Iannuzzi said. “Those are not going to be acceptable.”

Dan Cantor, executive director of the Working Families Party, which is supported by organized labor, said there was “no chance for a cap,” though he supported the idea of a circuit breaker, “which provides more property tax relief to individuals who need it.”

As for the commission itself, Mr. Cantor said, “some of their broader, more high-profile recommendations are likely to go unremembered.”

Mr. Suozzi, who has clashed with unions in Nassau, is trying to strike a conciliatory tone in his role as chairman, and Mr. Iannuzzi said that Mr. Suozzi had been “respectful and polite.”

Political support for a cap has been growing, and Mr. Suozzi said, “I’ve spoken with Governor Paterson and his staff, I’ve spoken with Shelly Silver and his staff and Joe Bruno and his staff.

“The thing that’s different from the past is that everybody agreed there’s a problem,” he added.

Whether they can agree on a solution remains to be seen.