A dispute in Albany over Governor Paterson’s proposal to cap growth in school property taxes has opened a surprising rift in the state Senate.

In a vivid illustration of the topsy-turvy world of state politics, the Senate Republican majority leader, Joseph Bruno, is siding with the teachers unions and blocking the measure, while the Senate Democratic leader, Malcolm Smith, is not only supporting a cap but says he wants to restrict taxes even more aggressively than the governor.

Mr. Bruno yesterday joined the Democratic speaker of the Assembly, Sheldon Silver, in opposing Mr. Paterson’s plan to impose a strict limit on how much districts outside New York City can raise property taxes each year.

During a press conference with Mr. Paterson, Mr. Smith, and other legislative leaders, who took a break from end-of-session negotiations to give an update on their lack of progress, Mr. Bruno criticized the governor’s bill as phony relief for homeowners and said he wouldn’t introduce it on the floor.

Instead, Mr. Bruno promoted an alternative plan that would “phase out” local property taxes by shifting billions of dollars in school costs to the state. Mr. Bruno has not said how the state would pay for it, and Assembly Democrats have refused to acknowledge its existence, let alone debate it.

“Everyone here is one-upping each other. Nothing is going to happen because we’re going to end up covering ourselves in posture,” Mr. Bruno said, in what appeared to be a moment of candor.

Mr. Silver is also blocking Mr. Paterson’s bill, but for a different reason. His concern is that it would lead to damaging cuts to New York’s public schools, which spend on average more per pupil than any other state. “I’m for a property tax cap, but I want to know that school districts have resources,” he said.

Mr. Paterson is calling for legislators to cap the annual growth in school property tax levies at 4%, arguing that a similar measure passed in Massachusetts in 1980 dramatically lowered local taxes in the Bay State.

According to a 2007 study by the Tax Foundation, New Yorkers pay 13.8% of personal income in state and local taxes, the third highest figure in the nation. Much of that amount is property taxes, which have been rising at a 7% clip since 2001. Property taxes outside of the city are 54% higher than the national average.

Mr. Smith, who represents a district in Queens, said he favors lowering the cap to 2%

“Everyone agrees to the need for relief of property taxes and we have to do it now,” Mr. Smith told the Associated Press. “I’m in this business to do what I think is right, not just what people tell me,” he said.

Minority leaders in the Senate and Assembly, who have little say over the fate of legislation, don’t have to worry as much about the consequences of flouting the will of interest groups.

Still, Mr. Smith’s comments surprised and angered his conference members, many of whom have said they are against a cap, including the ranking member of the Senate education committee, Suzi Oppenheimer. The conference debated the issue on Tuesday but hasn’t taken a position.

“We’re shocked,” a Democratic legislator said.

Mr. Smith’s contentious stance may also reflect a revised political calculation about voter attitudes toward taxes.

As majority leader, Mr. Bruno, 79, for years has successfully claimed the mantle of tax cutter without alienating the state’s largest teachers union, New York State United Teachers, which between 2005 and 2008 pumped more than $650,000 into his conference coffers.

By siding with the governor, Mr. Smith is putting Mr. Bruno on the spot on an issue that could come back to haunt the Republican leader on Election Day, when his party tries to hold onto its slim majority.

While the Republicans rely heavily on the support of organized labor, voter anger about the rise of taxes and the heightened focus on the idea of a cap may backfire on Republicans, especially those in the battleground suburban districts where the problem of property taxes is most acute.

Mr. Bruno’s opposition to a cap has been questioned by even some Republicans in his conference, including one of its rising stars, Martin Golden of Brooklyn.

“Some people are squeamish about it because of the unions,” Mr. Golden said of the tax cap. “Golden supports it 100%. I think Joe would do it if there’s enough screaming and yelling.”