“If we don’t get Central Park, we won’t have a rally,” the national coordinator for the largest expected protest of the Republican National Convention told New York State Supreme Court Justice Jacqueline Silberman yesterday.

Leslie Cagan delivered her ultimatum at an emergency state court hearing to determine whether the group, United for Peace and Justice, can use Central Park for a protest during the Republican National Convention. She also left open the door for protesters to choose their own site.

“People may go to the park, it’s up to them,” she said at a press conference after the hearing.

It was a nearly identical statement to the one offered by the National Council of Arab Americans, whose plan to rally on the Great Lawn on August 28 was rejected in federal court.

Police are aware of the possibility of spontaneous protests in Central Park.

“We’ll enforce the law, but we’ll deal with the situation with common sense,” said the deputy commissioner for public information, Paul Browne. He said police have no reserve force to deploy in the event of a problem in Central Park, but there are plans for additional uniformed and plainclothes officers to patrol the park on foot, scooter, and bicycle.

As long as protesters do not disturb other people using the park, do not use an amplified sound system, and do not congregate in groups of 20 or more, the police will not bother them.

While awaiting today’s decision, Ms. Cagan had said that United for Peace and Justice, which expects 250,000 protesters, will march up Seventh Avenue past the convention at Madison Square Garden no matter what the decision. She also said they’re “considering several different options.”

The coalition originally asked for the use of Central Park in December, were denied by the Department of Parks and Recreation in May, and finally accepted a city ultimatum to march past the Garden and rally on West and Chambers streets in July. A few weeks after accepting, the group changed its mind and reapplied for Central Park. They were immediately rejected.

The group’s lawyers cited numerous uses of the Great Lawn and Central Park in which the number of attendees exceeded that of the demonstrators, like the 1991 Paul Simon concert, which police estimated at the time was attended by 750,000 people, and their papers addressed the centrality of the park as a place of protest.

“Central Park is our Town Square,” said one lawyer, Jeffrey Fogel.

But the Great Lawn has been under a new management plan since its $18.2 million renovation from 1995 to 1997, and the Parks Department has limited use of the lawn to five events, four of which are annually held by the New York Philharmonic and the Metropolitan Opera.

City attorneys centered their defense on the short time-frame until the proposed date of the rally, just five days. They noted that it took the Parks Department 10 days to prepare for a privately funded Dave Matthews concert held in 2003. It took the Parks Department four hours to get 70,000 fans into the Great Lawn in a way that protected the grass.

Judge Silberman’s demeanor was respectful in letting lawyers for United for Peace and Justice make their case, but her questions for the plaintiffs were pointed and targeted issues of whether the group could post a bond sufficient to cover damage and whether the group’s marshals could manage the crowd and keep protesters from overcrowding any one part of the park.

Though the Parks Department does not require a bond for use of the Great Lawn, the judge seemed to indicate that if the group could come up with a large enough bond to cover damage, she might grant the petition. Ms. Cagan suggested that they could produce $50,000, less than one third of the $160,000 needed to make repairs after the Dave Matthews Band concert.

Security plans for the convention will be discussed today when the homeland security secretary, Tom Ridge, will be at Police Headquarters to view a demonstration of new security technology and give part of a security briefing. Also on hand will be Mayor Bloomberg and Governor Pataki.