Joseph J. Lhota, a former deputy mayor, remembered the endorsement debate differently, suggesting that Hauer had put politics over principles in a way that "put his whole credibility in question."

Fred Siegel, the author of "The Prince of the City: Giuliani, New York and the Genius of American Life" (Encounter Books, 2005), said the trust that members of Giuliani's inner circle invested in each other was the reason no one apart from Hauer had ever emerged as even an occasional critic.

"The core of the administration was that these guys would always pull together," said Siegel, who once served as speechwriter for Giuliani. "Once a decision was made, that was it. There wouldn't be any second-guessing."

Giuliani and Hauer began their relationship in January 1996 when Hauer was hired to lead the new Office of Emergency Management, created to coordinate the city's response to crises. Hauer, who was little known before he became a Giuliani aide, had previously run emergency management programs for the State of Indiana and IBM.

In his book, Siegel describes Hauer, who is 6-foot-5, as "a big, plain-spoken and knowledgeable man" who "won widespread cooperation."

One of Hauer's first tasks was to find a home for an emergency command center to replace the inadequate facilities at police headquarters. Hauer suggested an office complex in downtown Brooklyn as a "good alternative" in a memorandum.

But Hauer said the mayor insisted instead on a site within walking distance of City Hall. Given that concern and others, Hauer said he decided that offices on the 23rd floor of 7 World Trade Center, next to the twin towers and just a few blocks from City Hall, seemed the best choice.

The site was immediately controversial because it was part of the trade center, which had already been the location of a truck bomb attack in 1993. City officials, though, including Hauer, have long defended their decision, even after the command center had to be evacuated during the 2001 terror attack.

Last week, in an interview with Fox News, Giuliani again faced questions about the site. He put responsibility for selecting it on Hauer.

"Jerry Hauer recommended that as the prime site and the site that would make the most sense," Giuliani said. "It was largely on his recommendation that that site was selected."

Hauer took immediate exception to that account in interviews. "That's Rudy's own reality that he lives in," he said. "It is not, in fact, the truth."

Hauer has also expressed concern about the level of support he felt from Giuliani, in particular when he tried to bridge the divide between the city's Police and Fire Departments, two disparate emergency response cultures that battled over turf.