Mitt Romney and John McCain are - in an increasingly bitter and personal struggle to control the campaign conversation before Florida's primary on Tuesday - and the Republican presidential nomination itself may go to the one who succeeds. Romney, the former Massachusetts governor and venture capitalist, casts himself as a business-savvy economic turnaround artist amid recession anxiety, while McCain, the Arizona senator and former prisoner of war in Vietnam, portrays himself as a courageous wartime commander in chief in a dangerous world. "He has an enormous disadvantage when it comes to the topics of changing Washington or fixing our economy," Romney said Sunday, arguing that he is far stronger than McCain on both issues. Countered McCain: "Even if the economy is the, quote, No. 1 issue, the real issue will remain America's security" - and, unlike him, Romney is deficient in that area. The two leaders for the Republican nomination essentially are beginning their national arguments here, ahead of a virtual national primary on Feb. 5. They are giving rank-and-file GOP voters a choice between what have historically been the party's two most important issues - the economy and national security. That's not an easy decision for many Republicans. Rudy Giuliani, the former New York mayor trying to salvage his candidacy, has been arguing that he offers a perfect combination - strength on the economy and on security - and is hoping to benefit from their squabbling. "Senator McCain and Governor Romney are doing such a good job of attacking each other, how about voting for somebody who's not attacking? Vote for me, Rudy Giuliani," he said in Cocoa Beach, Fla. In the past month, the economy has replaced national security as the top concern among Republican voters as financial market turmoil and a housing crisis prompted President Bush to push an economic stimulus package to prevent a recession. The shift works in Romney's favor and against McCain. So, Romney has spent the past week promoting his private sector credentials and arguing that McCain, who has served the country in the military and in Congress for most of his adult life, lacks economic know-how and qualifications as the country teeters on the brink of recession. McCain, in turn, has sought to resurrect the national security issue by trumpeting his decades-long experience on defense issues while arguing that Romney doesn't have the judgment needed in wartime. In a misleading attack, McCain also accused him of once wanting a timetable like the Democrats wanted for troop withdrawals. Their intense fight underscores the extraordinarily close Florida race and the stakes at hand. Polls show them battling for the lead in the state, which offers the winner a hefty 57 delegates to the party's nominating convention and momentum heading into the Feb. 5 contests. Long a muddle, the GOP nomination race has narrowed into a two-man contest between Romney and McCain. Giuliani has lost six straight contests. He has pinned his candidacy on a Florida win but is badly trailing and is facing money woes. Mike Huckabee, the former Arkansas governor, won the leadoff Iowa caucuses but hasn't prevailed since and is all but broke, barely playing in Florida. Romney won his native state of Michigan and two scarcely fought contests in Wyoming and Nevada. He needs a Florida victory to prove he can win in a hard-fought state and in a place where he doesn't have roots. McCain, who scored big wins in New Hampshire and South Carolina, wants Florida to cement him as the clear front-runner and open the financial floodgates to help him compete in the next contests. The race has grown hotter by the day. Romney stepped up his argument that he is best for the troubled economy. He dinged McCain for twice voting against Bush's tax cuts and cast the four-term senator as the consummate Washington insider who has failed to fix a broken Washington. "I've spent my life, 25 years, in the world of business," Romney said. "I know why jobs come and go." For days, McCain refused to engage. Instead, he emphasized his military background coupled with his economic proposals as he sought to argue that he offers not only fiscal conservatism but also national security experience. He claimed in a TV ad that he can "protect our shores and protect your pocketbooks." A debate Thursday night in Boca Raton was a civil affair. But the two campaigns were gearing up for an ugly weekend. Romney's campaign released a Web video that showed McCain saying, "I've always been for tax cuts. I have always, although I voted against the first tax cuts." Not to be outdone, McCain's team unveiled their own video of Romney's face superimposed on the windsurfing body of 2004 Democratic presidential nominee John Kerry. "Mitt Romney seems to change positions like the wind," the video says. The sparring spilled over Friday. McCain went on the offensive, saying: "I've been a leader. Americans want leaders. They don't want managers." Romney returned fire, arguing that voters aren't "looking for a talker or a committeeman or someone who loves to get together and debate." By Saturday, the debate spiraled even further downward. McCain said of Romney and Iraq: "Now, one of my opponents wanted to set a date for withdrawal that would have meant disaster." Then he added: "If we surrender and wave a white flag, like Senator Clinton wants to do, and withdraw, as Governor Romney wanted to do, then there will be chaos, genocide, and the cost of American blood and treasure would be dramatically higher." But Romney never supported the public date for withdrawal or a specific date for U.S. troops to return that Democrats advocated. He did, however, once say that Bush and Iraqi leaders need private timetables and benchmarks by which to gauge progress and help determine troop levels. That mischaracterization prompted a sharp rebuke from Romney: "That's simply wrong and it's dishonest, and he should apologize." He added: "He's trying desperately to change the topic from the economy and trying to get back to Iraq."