The protesters, most of whom lost loved ones on Sept. 11, tracked the Republican hopeful to two of his four stops and did their best to disrupt the festivities by raising questions about Giuliani's decision-making on Sept. 11, particularly his failure to replace long-faulty FDNY radios before that tragic day.

"Rudy, we ain't going away," said fire officers union chief Peter Gorman, who with other protesters has hit three Giuliani events in the city since March. Gorman is promising to extend the protests across the country with his national union, the International Association of Firefighters.

But if Giuliani was bothered by the protesters, who yelled "Shame!" at him as he left an event in Bay Ridge, Brooklyn, and at least once saluted him with a middle finger, he didn't show it.

"There isn't any part of me at all that resents it," the recently mellowed Giuliani told reporters in Queens. "(Sept. 11 was) a very, very traumatic, horrible experience. I lived through it. I watched people die. . . . So any anger that people displace about this, I have never had any resentment."

He also conceded, as he has in the past, that mistakes were made on Sept. 11.

For Giuliani, who celebrated his birthday Monday, the focus on Sept. 11 largely overshadowed what was otherwise a successful return to his original electoral base: the largely white, Catholic, middle-class neighborhoods outside of Manhattan.

The former mayor began with a breakfast on City Island in the Bronx, hosted a lunch in Douglaston, Queens, moved on to cocktails in Bay Ridge, then ended the day with a party on Staten Island.

Former Staten Island Borough President Guy Molinari, who heads Giuliani's New York campaign, estimated the day reaped $500,000 and predicted that none of the other nine GOP contenders for President would stage a primary fight in New York.

"They will exercise common sense," said Molinari, "and go someplace else."

Written by Daily News