ORLANDO, Fla. — John McCain accused Mitt Romney of wanting to set a timetable to withdraw U.S. troops from Iraq, drawing immediate protest from his Republican presidential rival who said: "That's simply wrong and it's dishonest, and he should apologize."

The heated exchange underscored the growing intensity of the GOP race ahead of the state's pivotal primary. A fairly civil debate over economic records and leadership credentials spiraled into an all-out showdown as the two campaigned along the state's southwest coast.

Polls show McCain and Romney locked in a tight fight for the lead in a state that offers the winner a hefty 57 delegates to the GOP's nominating convention next summer and a shot of energy heading into a virtual national primary on Feb. 5.

In Orlando, Rudy Giuliani, the former New York mayor trailing in polls and trying to climb his way back into the leaders' pack, sought to take the high road. "If you listen to my opponents, it's getting kind of nasty," Giuliani said in Orlando. "I'm going to try to remain positive."

SPARRING OVER WAR

With economic troubles dominating the race, McCain opened the new line of criticism against Romney at his first event of the day in Fort Myers, Fla., and sought to shift the campaign back to his strength, national security, and away from Romney's, the economy.

First, he slapped at Romney without naming him during a question-and-answer session with Floridians, saying: "Now, one of my opponents wanted to set a date for withdrawal that would have meant disaster."

Minutes later to reporters, the Arizona senator was more direct: "If we surrender and wave a white flag, like Sen. Clinton wants to do, and withdraw, as Gov. Romney wanted to do, then there will be chaos, genocide, and the cost of American blood and treasure would be dramatically higher."

Asked about the comment in Land O' Lakes, Fla., Romney bristled.

"That's dishonest, to say that I have a specific date. That's simply wrong," he said. "That is not the case. I've never said that."

The former Massachusetts governor added: "I know he's trying desperately to change the topic from the economy and trying to get back to Iraq, but to say something that's not accurate is simply wrong — and he knows better."

Later in Sun City, Fla., McCain stuck to his assessment and said: "The apology is owed to the young men and women serving this nation in uniform."

He said he was quoting Romney as favoring a "timetable" for withdrawal and argued that he was not misquoting Romney, saying, "Clearly, the impression was that he was ready to set a date for withdrawal."

But Romney quotes circulated by McCain's campaign didn't show Romney making that exact comment — nor did aides back up McCain's earlier comment that suggested that Romney "wanted to set a date for withdrawal."

AGREES WITH PETRAEUS

In an interview with ABC News in 2007, Romney said: "There's no question that the president and (Iraqi) Prime Minister al-Maliki have to have a series of timetables and milestones that they speak about. But those shouldn't be for public pronouncement. You don't want the enemy to understand how long they have to wait in the weeds until you're going to be gone."

While Romney has never set a public date for withdrawal, he has said that he agrees with Gen. David Petraeus, the top U.S. commander in Iraq, that U.S. troops could move to more of an oversight role in 2008.

McCain, for his part, has been a staunch supporter of the Iraq war and advocated more troops on the ground for years before Bush embraced that position last year and ramped up the number of U.S. forces in Iraq. The buildup helped curb violence in Iraq, and McCain has not been shy about claiming credit for the strategy's success.

Romney aides labeled McCain's charge "stunningly false," while McCain aides portrayed his Iraq comments as part of a broader effort in the coming days to question Romney's leadership, foreign policy experience and judgment.

A former venture capitalist and business consultant, Romney has spent the past week arguing that he is the Republican best able to right a troubled economy, given his 25-year record in the private sector. He's argued that McCain, who has spent much of his life in the military and in Congress, doesn't have the qualifications necessary to lead the country out of a potential recession.

McCain, in turn, has sought to beat back Romney on the issue by arguing that a president needs to be ready to lead and qualified on both national security and economics, and he offers both — despite having previously acknowledged that the economy is not his strongest suit.

He also sought to rebut Romney's criticisms in an unusual fashion: he dispatched high-profile surrogates to talk with the press corps traveling with the former governor. Among them: former Pennsylvania Gov. Tom Ridge and former Massachusetts Gov. Jane Swift.