Mitt Romney marched ahead Wednesday with a commanding lead in the US Republican race for the White House after trouncing his main rival Newt Gingrich in a bitterly-fought Florida primary.
The margin of victory -- 46 percent to 32 percent -- dealt a bitter blow to former House speaker Gingrich, who faces a Herculean task to try to catch up with Romney, a multimillionaire businessman and former Massachusetts governor.
Gingrich, 68, shocked the party establishment when he thumped Romney, 64, in South Carolina earlier this month, but his support sank fast in the larger and more diverse state of Florida, and Romney now has all the momentum.
Romney's double-digit win in the Sunshine State demonstrated his strength in a key general election battleground, and he used his victory speech to urge Americans to evict President Barack Obama from the White House in November.
"Mr. President, you were elected to lead. You chose to follow, and now it's time for you to get out of the way," he said, to chants of "Mitt! Mitt! Mitt!" from hundreds of supporters in a packed Tampa ballroom.
"President Obama wants to fundamentally transform America and make it something perhaps we wouldn't recognize. I want to restore to America the values and principles that made us the hope of the Earth," Romney said.
It was a warning shot at Democrats who have been salivating over the increasingly caustic tone of the Republican campaign -- marked in Florida by a heavy exchange of increasingly personal attacks between Romney and Gingrich.
"A competitive primary does not divide us, it prepares us and we will win," Romney said. "When we gather back here in Tampa seven months from now for our convention, ours will be a united party with a winning ticket for America."
The economy seemed to be on the minds of many voters in Florida, including businessman Paul Jackson, who said he voted for Romney.
"I voted for him because I think he has the best chance of beating the president -- the current president.
"I don't agree with everything that he stands for, but I need to see a change that satisfies my selfish needs as a small business owner," he said.
Florida has been badly hit by the "Great Recession" wrought by the 2008 financial crisis -- unemployment is close to 10 percent and the state was at the epicenter of the housing collapse.
Many residents have seen their homes repossessed or have mortgages now worth more than the value of their homes.
Despite the stinging defeat, Gingrich promised to wage a long-haul battle all the way to the August 27-30 convention, which will formally crown a nominee to go head-to-head against Obama on November 6.
"It is now clear that this will be a two-person race between the conservative leader, Newt Gingrich, and the Massachusetts moderate," he told supporters in Orlando, referring to Romney.
Gingrich is desperate for Rick Santorum, who was running third on Tuesday with 13 percent, to quit, as he believes the former Pennsylvania senator's conservative support would swing behind him and allow him to usurp Romney.
But Santorum, already in Nevada after giving up on Florida to focus his meager resources elsewhere, showed no sign of conceding and instead sent out a defiant message to the Gingrich camp.
"We need someone who can be a conservative nominee," he said in Las Vegas.
"In Florida, Newt Gingrich had his opportunity. He came out of the state of South Carolina, he came out with a big win and a lot of money.
"He said: 'I'm going to be the conservative alternative. I'm going to be the anti-Mitt.' It didn't work. He became the issue. We can't allow our nominee to be the issue in the campaign."
After the South Carolina setback, Romney used his much deeper campaign war chest to unleash an unrelenting barrage of negative ads in Florida.
Hitting Gingrich on ethics, Romney also frequently mentioned the former speaker's work as a highly paid consultant for mortgage giant Freddie Mac -- which is seen by some as complicit in the housing meltdown of 2008.
With seven states voting in the next four weeks, Romney's deep pockets and political organization could play a key role as the candidates battle on multiple fronts.
Romney won five of those seven states in 2008, despite losing the eventual nomination to Senator John McCain.
The next contests will take place on Saturday in Nevada and Maine, where veteran Texas congressman Ron Paul -- trailing fourth and last in Florida with just seven percent of the vote -- is hoping for a much stronger showing.