Lawmakers seeking to change the city’s term limits law will have to contend with a new voice of opposition.

Launched yesterday in front of City Hall, the People Have Spoken Coalition, a collection of politicians and community leaders, is pledging to fight changes to term limits restrictions through rallies and, potentially, legal action. It is the latest sign of organized resistance to a term limits repeal, coming on the heels of a like-minded television ad campaign that ran during the weekend.

“We call upon our fellow New Yorkers — anyone and everyone — to join us in this important citywide effort in maintaining the existing law,” a former head of the New York Civil Liberties Union, Norman Siegel, who helped organize the event, said. “The City Council should not undo the people’s will.”

Mr. Siegel was joined by several local leaders, including City Council Member Bill de Blasio and state Senator Eric Adams.

New Yorkers voted to support term limits in two referendums during the 1990s. Now, with about two-thirds of the City Council set to be forced from office next year, along with the popular Mayor Bloomberg, legislators have discussed changing the law anyway.

No such bill has yet been submitted, but those in favor of term limits are trying to beat it to the punch. A billionaire businessman, Ronald Lauder, financed a television ad campaign this weekend comparing politicians to diapers that need to be changed regularly. Mr. Siegel said the coalition announced yesterday will coordinate with Mr. Lauder’s group, New Yorkers for Term Limits.

The television campaign was criticized yesterday by a Brooklyn council member, Lewis Fidler, who supports repealing term limits. The ads attack the council, he said, but they should be directed at the mayor, who has refused to commit to a position on the issue. Mr. Bloomberg recently said he would consider signing a bill extending term limits, a departure from previous statements endorsing the current law.

“For Mr. Lauder to script an ad that ignores his friend the mayor and focuses attention on the City Council is a little disingenuous,” Mr. Fidler said.

A spokesman for Mr. Lauder, Nelson Warfield, responded that “the City Council is such a widespread disaster, it’s hard to find a better target.”

According to a survey conducted by the New York Times, a majority of council members favor repealing the current law. Mr. Fidler said term limits result in “bad government,” partly because they empower civil servants and lobbyists who outlast elected officials.

At the coalition event, Mr. Adams praised “movement” in the city’s political class.

“If we can tell the president of the United States two terms is enough, then we can say it to our City Council, our borough-wide elected, and our statewide positions as well,” he said. “The city will not die without Bloomberg.”

Mr. Siegel said that in addition to grassroots organizing, the coalition may file a lawsuit as a last resort.