Mitt Romney easily won the Florida Republican primary Tuesday, cementing himself as the frontrunner over rival Newt Gingrich.
Unofficial results show Romney won 47 per cent of the vote compared to 32 per cent for Gingrich.
Rick Santorum and Ron Paul garnered 13 per cent and seven per cent of the vote respectively, but had largely ignored Florida.
"Primary contests are not easy and they're not supposed to be," Romney said during a victory speech in Tampa before going to target U.S. President Barack Obama.
"A competitive primary does not divide us, it prepares us, and we will win .... Mr. President, you were elected to lead, you chose to follow, and now it's time for you to get out of the way."
The Republican nomination race has grown increasingly negative between Gingrich and Romney, and appears to be heading for a long, drawn-out fight. Gingrich said the race wouldn't be over until June or July "unless Romney drops out earlier."
Santorum and Paul have moved on to Missouri, the next state where candidates will compete to become the nominee to square off against Barack Obama in the 2012 presidential election. Paul gets much of his support from independent voters, but the Florida primary only allowed registered Republicans to vote.
The big win in Florida secures Romney's status as the first-place contender -- a position that had been wavering recently as former house speaker Gingrich gained momentum to challenge the former Massachusetts governor.
Gingrich won the South Carolina primary on Jan. 21 in a stunning upset, just ahead of the Florida primary.
But in recent days Romney has regained his footing as he heads into the "first in the west" Nevada caucuses this weekend. Romney easily won there in 2008 during his first run for the Republican nomination.
Both Romney and Gingrich have taken advantage of Florida's lax laws on advertising spending. Romney and his supporters spent roughly $16 million on TV ads in Florida alone, and Gingrich and his supporters spent $14 million.
Most of Romney's ads have taken aim at Gingrich -- often effectively.
Two strong debate performances by Romney also helped him to regain his lead.
Florida is the fourth and largest state to hold a primary and the winner will take all 50 delegates that are up for grabs.
Romney, who is better funded than Gingrich and has the support of much of the Republican party, is typically seen as the strongest contender to face off against Obama in the next election.
However, Romney has had trouble gaining traction with conservative Republicans who question where he stands on key issues such as abortion, gay rights and gun control.
The health insurance plan in Romney's home state of Massachusetts also bears a close resemblance to Obama's national plan, which is widely despised by Republicans.
Romney also faced major questions about his vast personal wealth earlier in the campaign, but eventually released his tax records -- a move that largely shut down the criticism.
Romney has characterized his opponent as an untrustworthy influence peddler with ties to mortgage giant Freddie Mac.
Gingrich has painted Romney as an imposter and has vowed to fight to the end, regardless of the attacks he faces.
"He can bury me for a very short amount of time with four or five or six times as much money," Gingrich said in a television interview. "In the long run, the Republican Party is not going to nominate ... a liberal Republican."
