“No contract, no convention. No contract, no convention.”

So shouted off-duty policemen in their latest rant outside an AIDS clinic in Midtown yesterday in anticipation of Mayor Bloomberg’s arrival to open a new model for HIV/AIDS services.

The group has been dogging Mayor Bloomberg for weeks, pressuring him into giving them a double-digit raise and restarting stalled contract talks. The mayor has said he won’t be intimidated and has told the members that yelling at him outside public events is not the way to get him to relent.

Yesterday’s demonstrators wore blue T-shirts and shouted from behind a police barricade. The group of more than two dozen off-duty police officers blocked the sidewalk and spilled out onto Eighth Avenue, snarling traffic.

Their uniformed brethren, out in force to protect the mayor, moved pedestrians along and allowed the off-duty police to take over the sidewalk. After the mayor hastily departed, some of the uniformed cops grinned and shook hands with the off-duty rank and file.

An NYPD spokesman, Paul Browne, denied there was a double standard.

“The Police Department will have the same standards for any group regardless of who they are. Department policy applies to everybody,” he said. He declined to comment on yesterday’s demonstration, though he acknowledged that no one is permitted to shut down a street or block people from walking on the sidewalk without a permit.

In response to a question about why the protesting officers were allowed to block the sidewalk and spill into the street, Mr. Bloomberg said, “If there are groups of demonstrators who aren’t following their rules, I am sure the police commissioner will redeploy his officers” to make sure they do.

Mr. Bloomberg has said he would not let the police and fire unions bully him into giving them a bigger pay increase by threatening a strike during the Republican National Convention at the end of the month.

He said yesterday he didn’t expect a wildcat action. “They won’t do that,” he told reporters. Members and union leaders say they have not ruled anything out.

Though the mayor has been trying to take the heat out of the situation, the union seems determined to escalate. Chants have become more taunting and disrespectful.

When the mayor hops into his Suburban after events, they yell “Run Away, Mikey, Run Away.” Their latest slogan: “A Billionaire Who Doesn’t Care.”