By DAVID ESPO and LIZ SIDOTI, Associated Press Writers
MIAMI - Sen. John McCain won a breakthrough triumph in the Florida primary Tuesday night, gaining the upper hand in the battle for the Republican presidential nomination ahead of next week's contests across 21 states. Former New York Mayor Rudy Giuliani appeared ready to quit the race.
"It shows one thing. I'm the conservative leader who can unite the party," McCain said in a brief interview with The Associated Press.
"It's a very significant boost, but I think we've got a tough week ahead and a lot of states to come."
The victory was worth 57 national convention delegates for McCain, a winner-take-all haul that catapulted him ahead of Romney for the overall delegate lead.
Giuliani ran third, his best showing of the campaign but not nearly good enough for the one-time front-runner who decided to make his last stand in a state that is home to tens of thousands of transplanted New Yorkers.
In remarks to supporters in Orlando, he referred to his candidacy repeatedly in the past tense — as though it was over. "We'll stay involved and together we'll make sure that we'll do everything we can to hand our nation off to the next generation better than it was before," he said.
Former Arkansas Gov. Mike Huckabee trailed, but told supporters he would campaign on. Texas Rep. Ron Paul was fifth, and last.
Romney, who has spent millions of dollars of his personal fortune to run for the White House, also vowed to stay in the race.
"At a time like this, America needs a president in the White House who has actually had a job in the real economy," he told supporters in St. Petersburg.
Florida marked the end of one phase of the campaign, the last in a series of single-state contests.
The campaign goes national next week, with 21 states holding primaries and caucuses on Tuesday and 1,023 party convention delegates at stake.
Returns from 73 percent of the state's precincts showed McCain, the Arizona senator, with 36 percent of the vote and Romney, the former governor of Massachusetts, with 31 percent.
The victory was another step in one of the most remarkable political comebacks of recent times. McCain entered the race the front-runner, then found his campaign unraveling last summer as his stands in favor of the Iraq War and a controversial immigration bill proved unpopular.
The war gradually became less of a concern after President Bush's decision to increase troop deployments began to produce results. McCain also sought to readjust his position on immigration.
By the time of the New Hampshire primary, he was primed for victory, and got it. He won the South Carolina primary last week, taking first place in the state that had snuffed out his presidential hopes in 2000.