By Jonathan Allen, CQ Staff

Fresh off his victory in the Florida primary, Sen. John McCain got a boost Wednesday when fellow Republican Rudy Giuliani dropped out of the presidential race and threw his support to the Arizona senator.

Appearing with McCain at the Ronald Reagan Library in Simi Valley, Calif., Giuliani called McCain (who was tortured as a POW during the Vietnam War) a hero and said no other candidate could compete for his backing.

“I made it clear at different times during this campaign that had I not decided to run  . . .  the one person in this country that I clearly would have supported for president of the United States would have been John McCain and that came from the heart,” Giuliani said. “If I endorsed anyone else, you would say I was flip-flopping.”

Giuliani’s departure is likely to mean more votes for McCain from moderates, some of whom had been siding with the former New York mayor.

For McCain, whose campaign was in debt through the end of 2007 according to campaign records released Wednesday, it may be a tie to Giuliani’s donors that proves most important. Mitt Romney , McCain’s chief rival for the GOP nomination, is awash in his own cash, the result of a career in the business world.

Giuliani centered his campaign on national security issues, attempting to build on his reputation as a strong leader in the immediate aftermath of the Sept. 11, 2001 terrorist assault on New York and Washington. His liberalism on many social issues hurt him with the party’s conservatives, and he failed to finish in the top two in any of the early primary states.

The tally of 15 percent from his distant third-place finish to McCain and Romney in Florida Tuesday served as the writing on the wall that a continued Giuliani candidacy would be for delegates, not the nomination.

While Giuliani’s candidacy split off some moderate Republican voters from McCain, former Arkansas Gov. Mike Huckabee has been dividing conservatives with Romney. Huckabee shows no signs of dropping a candidacy that appears to be helping McCain by hurting Romney.

While McCain appears likely to pick up Giuliani voters, the winnowing of the field could also bring to Romney fiscal and social conservatives intent on stopping McCain.

“As long as Romney is in the race, I think conservatives are generally going for him,” said a conservative Republican aide on Capitol Hill. That aide downplayed the importance of the Giuliani endorsement for McCain: “Giuliani doesn’t bring anything. He couldn’t even attract people to his own campaign,” the aide said.