Already in the midst of a storm for denying permits to protesters, the city finds itself caught in a squall over a union rally permit it granted.

The union representing the 1,100 IRS workers at 26 Federal Plaza, the National Treasury Employees Union, thought all its papers were in order when the city issued it a sound permit for a Thursday gathering of 500 people on the sidewalk between Duane and Worth streets in front of the Jacob Javits Federal Building.

But the General Service Administration, which runs the building, says it owns the part of the sidewalk delineated by stout black posts, called bollards, which divide the sidewalk into a roughly 20-foot-wide inner portion and 10-foot-wide outer portion, and it won’t let the accountants, collection agents, and lawyers of NTEU 47 use the space for their rally.

“They’re pushing us into the gutter,” said the union director, Frank Heffler.

The city and federal government scrimmaged over sidewalk space many times before, most recently during the Martha Stewart trial when a federal judge wanted to close the sidewalk to the press, but the police refused to comply with the order. The judge eventually backed down.

The bollards on the sidewalk at the Javits building were installed in 2003,at the same time the federal government took over Duane Street north of the building, to prevent truck bombs from rolling right up to the building entrance.

“At 26 Federal Plaza, we don’t permit demonstrations and rallies on government property due to security concerns,” said the assistant regional administrator for GSA, John Scorsia.

But the district director of Federal Protection Services, Chris Pappas, said he’d done a walk-through with representatives of NTEU and “security is not an issue with this rally.”

Presented with that information, Mr. Scorsia answered all subsequent queries with only “no comment.”

Mr. Heffler thinks the permit was denied because the rally intends to call attention to the outsourcing of hundreds of union jobs. Up to 25% of tax collection and information technology services will be contracted out, costing New York hundreds of federal jobs, Mr. Heffler said.

To prove his point, at the end of their last discussion, Mr. Heffler says Mr. Scorsia told him he had “made up his mind,” and that having a rally “is not what the administration’s agenda wants.”

Mr. Scorsia would not confirm or deny this comment, but if true, it would suggest he has rejected the permit because of the content of the rally, which is illegal.

Complicating matters further, the city believes the GSA doesn’t have authority over the sidewalk. A police source told The New York Sun the city manages the sidewalk all the way to the stairwell leading to the building’s main entrance.

Members attending the rally will be on their lunch hour, so several likely will stand on the wrong part of the sidewalk. The federal government has its own police force that could enforce the limitation, but Mr. Scorsia did not say what he would do if the crowd overflowed.