Green, now president at Air America Media, said civic and labor officials had discussed mounting a pro-term-limits campaign should Bloomberg seek to overturn the law.
"He's picked a fight. And now he'll get one," he said.
Dick Dadey, executive director of the good-government group Citizens Union, said that any change to the law should be made by voters, not legislators. "There are compelling reasons to consider changing the law. But the will of the voters is sacrosanct on this issue," he said.
Not even 9/11 swayed the support many New Yorkers have for the term-limits law.
With his second term nearly over, then-Mayor Rudy Giuliani suggested overturning the term-limits law but ultimately decided against it. Even in the wake of the attacks, with Giuliani's approval rating at 90%, one poll found that 55% of New York City voters opposed repealing term limits.
Any change in the law would send shock waves through the ranks of the city's politicians, many of whom have been campaigning for different jobs, including Bloomberg's. The law currently on the books will force the mayor from office at the end of next year, as well as the city comptroller, two-thirds of the city council and the city's public advocate.
Democrats lining up to run for mayor include city Comptroller William Thompson, city council speaker Christine Quinn, U.S. Rep. Anthony Weiner and city councilman Anthony Avella. On the GOP side are supermarket magnate John Catsimatidis and lawyer Bruce Blakeman.
Bloomberg spent some $155 million on his first two campaigns, winning re-election by 20 percentage points in 2005.
John Collins, a spokesman for Weiner, said the news did not change the Queens congressman's intention to run for mayor.
"This is highly speculative," Collins added. "It's illegal to run for a third term."
Thompson called Bloomberg's plan a "terrible idea."
"This isn't about a person," he said. "Other leaders could move this city forward also."