A week after reneging on a compromise with the city, anti-war group United for Peace and Justice filed suit in state Supreme Court yesterday in a final attempt to use Central Park as a protest site on the eve of this month’s Republican National Convention.

The group is seeking an injunction against the city, which has refused to grant permission for a rally on the park’s Great Lawn, citing excessive crowd size and security concerns. The suit couches its argument in a Constitutional context, arguing that protesters’ rights to free speech and assembly have been violated.

“The grounds upon which the city has rested its denial of the permit are a pretext, a sham, and are frankly an outrage to citizens of this country who believe in the Constitution,” said counsel Jeffrey Fogel of the Center for Consitutional Rights, which filed the suit along with the New York Civil Liberties Union.

“One of the purposes of public spaces in our country is for the free expression of ideas and the sharing of ideas among citizens. That is the essence of a real democracy,” Mr. Fogel said.

The appeal brought no sympathy from City Hall yesterday.

“We are not going to give a permit for Central Park,” Mayor Bloomberg said yesterday. “I’ve said that many times. I don’t know how many times I’ve got to say it.”

“If the courts were to order us to do so, we would follow the law, but Central Park cannot accommodate a protest of another quarter of a million people in addition to all the other protests and all the people who are in Central Park on a normal Sunday,” the mayor said.

United for Peace and Justice originally filed a request in June 2003 to hold a protest on the Great Lawn during the convention, with an expected turnout of 250,000. That request was rejected by the city over concerns about crowd size and potential damage to the park.

Last month, after weeks of negotiations, both sides agreed on the West Side Highway at Chambers Street as a suitable site for the protest. But United for Peace and Justice abruptly pulled out of the agreement last Tuesday, citing criticism from its members, concerns over low attendance, and a lack of city assistance.

“We said we would take the West Side Highway after we were bullied by the police commissioner and the mayor,” Leslie Cagan, national coordinator of United for Peace and Justice, said yesterday. “We then did more research and found in fact, it couldn’t work.”

One observer warned that the protesters could be working against their own cause.

“If they win [the lawsuit] and the demonstrations get out of hand, they’ll be helping George Bush get elected,” said political consultant Hank Sheinkopf, who said that a violent protest would turn off voters.