MIAMI - Sen. John McCain won a breakthrough triumph in the Florida Republican primary Tuesday night, edging past former Massachusetts Gov. Mitt Romney and seizing precious campaign momentum for next week's string of contests across 21 states.
Former New York Mayor Rudy Giuliani was running third and headed for the exits. Officials familiar with events said his aides were in discussions with McCain's advisers on a possible endorsement later in the week.
Mike Huckabee was running fourth and pledged to campaign on. Texas Rep. Ron Paul was far behind in last place.
Returns from 62 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.
McCain's victory was his first-ever primary win in a state that allowed only Republicans to vote. His previous victories, in New Hampshire and South Carolina this year, and in two states in 2000, came in elections open to independents. He campaigned with the support of the state's two top Republican elected officials, Gov. Charlie Crist and Sen. Mel Martinez.
Romney's only primary win so far was in Michigan, a state where he grew up and claimed a home-field advantage. He also has caucus victories to his credit in Wyoming and Nevada.
A survey of voters as they left their polling places showed the economy was the top issue for nearly half the Republican electorate. McCain led his rival among those voters, blunting Romney's weeklong effort to persuade Floridians that his background as a businessman made him best-suited for heading off a recession.
McCain also was benefiting from the support of self-described moderates, as well as older voters and Hispanics. Giuliani ran second among Latino voters, according to preliminary exit poll data.
Romney was favored by voters opposed to abortion and to easing the path to citizenship for illegal immigrants.
About 40 percent of self-described conservatives supported him, as well, compared to about 25 percent for McCain.
The poll was conducted by Edison Media Research and Mitofsky International for The Associated Press and the television networks.
Sen. Hillary Rodham Clinton won the Democratic race, an event that drew no campaigning by any of the contenders - and awarded no delegates to the winner.