"The people have the right and deserve the opportunity to make this decision," Golisano said.
The Buffalo Sabres owner and philanthropist ranks as the 281st richest American with a net worth of $1.6 billion, by Forbes magazine estimates.
Bloomberg declared earlier this month that he wanted another four years in office and would seek to change the term-limits law so that he could run again. With a net worth estimated at $20 billion, the former CEO ranks as the eighth richest American and says he believes New Yorkers need him to stay on to manage the city through the years after the financial crisis.
Golisano praised Bloomberg's reign but said voters must have the chance to consider any change to term-limits law.
"No matter how great of a job he's done, the people in the end must make the decision on this term-limit issue," Golisano told reporters.
The public twice approved term-limits in the 1990s. The City Council has fast-tracked the mayor's bill and could vote as early as Thursday, although that was looking less likely. Council Speaker Christine Quinn, who backs the Bloomberg plan, told Democratic members of the council on Monday that the vote was not on the agenda yet for Thursday, which typically means she does not have enough support to pass a bill.
Bloomberg told reporters on Monday he welcomes Golisano's voice in the debate. However, his close political adviser, Kevin Sheekey, met with a Golisano aide last week to try to persuade the billionaire to keep out of it.
Opposition to Bloomberg's efforts has been gaining momentum in the two weeks since he announced his plans.
On Monday, the Working Families Party, which has organized part of the opposition effort, targeted undecided City Council members with giant posters in their districts, urging constituents to call the lawmakers.
Until Golisano emerged to take up the cause, the opposition campaign has been largely grassroots, without a major source of financing that would enable a widespread media effort.
The founder of Paychex Inc., a payroll-processing company, has unsuccessfully run for governor three times. He has advocated legalizing marijuana for medicinal use, and set a nationwide record for spending on a gubernatorial campaign - $73.9 million during the 2002 race.
His philanthropy has benefited hospitals and educational institutions. He has also spent his money on a statewide anti-casino blitz, and this year said he would spend $5 million to fund the campaigns of state Legislature candidates willing to take on special interests.
Golisano declined several times to say how much he was prepared to spend on a the term-limits campaign, but he made clear there may be several levels to his involvement.
If the council were to pass Bloomberg's term-limit change, Golisano said it was possible he would help finance legal challenges. He also indicated that, down the road, he might throw his money behind candidates challenging council members or others who support Bloomberg's bill.
Another New York billionaire, Ronald Lauder, had danced with the idea of fighting Bloomberg's efforts, but the mayor won him over by offering him a deal. In exchange for Lauder's support, Bloomberg invited Lauder to sit on a commission he will appoint down the road to study the term-limits law again and perhaps put it before the voters.
Bloomberg has argued that it is too late now to let voters have their say before the 2009 mayoral race. The deadline for putting it on this year's ballot has passed, and a special election would be too costly and turnout would be too low, Bloomberg says.
