Having soundly defeated former House speaker Newt Gingrich in the Sunshine State's primary, multimillionaire Romney headed to the western battleground of Nevada, but his controversial comments threatened to slow his momentum.
"I'm not concerned about the very poor. We have a safety net there. If it needs repair, I'll fix it," said Romney, a wealthy businessman who last week acknowledged earning $20 million in 2010.
"I'm not concerned about the very rich, they're doing just fine," Romney, a former venture capital boss who lives off his investments, told CNN.
"I'm concerned about the very heart of America, the 90-95 percent of Americans who right now are struggling and I'll continue to take that message across the nation."
The remarks came as the race for the right to take on Democratic President Barack Obama in November widened into more states, and were quickly seized on by his opponents.
The Democratic National Committee issued a message that said the remarks by the former Massachusetts governor were his latest dig at the poor and a "shallow attempt to show concern for the middle class."
And Gingrich, who lost to Romney by more than 14 percentage points in Florida, seized his chance to get back at his rival.
"I am fed up with politicians in either party dividing Americans against each other. I am running to be president of all the American people and I am concerned about all of the American people," Gingrich said in Nevada.
Romney has previously been criticized for failing to connect with ordinary voters who are struggling to make ends meet as unemployment lurks around 8.6 percent and the US economy gropes its way out of the recession.
His latest gaffe comes amid a fierce debate in the United States about widening income disparities ahead of the election.
Romney swiftly tried to explain his remarks, telling reporters traveling with him on his plane that they should consider everything he said, rather than just part of the sentence.
"Of course I'm concerned about all Americans... poor, wealthy, middle class, but the focus of my effort will be on middle income families who I think have been most hurt by the Obama economy," he said later.
As the first western state in the 2012 Republican nomination battle, Nevada thrusts new demographics and issues into the limelight, including concerns over illegal immigration, the environment and natural resources.
Like Florida, the "Silver State" has been badly hit by the recession with soaring unemployment and a real estate industry on its knees following the housing market meltdown.
Romney, who won handily here in the 2008 White House race, will be boosted by the large Mormon population. Four years ago, 26 percent of Nevada Republican caucusgoers were Mormon and 95 percent of them voted for Romney.
Nevada holds its caucus vote on Saturday, along with a similar caucus in Maine, while five other US states will hold votes in the coming month.
Gingrich, 68, had shocked the party establishment when he thumped Romney, 64, in South Carolina last month, but he was outpunched in Florida by his opponent's deeper pockets and superior political organization.
In a sign of how bitter the campaign has become, former Georgia lawmaker Gingrich broke with tradition by neither congratulating Romney nor calling him after the vote.
Instead, Gingrich vowed to wage a long-haul battle all the way to the August 27-30 convention, which will formally crown the party's nominee.
The two other Republicans still in the race -- Texas representative Ron Paul and Pennsylvania's former senator Rick Santorum -- gave up on Florida and have been busy canvassing in Nevada.
In Florida, Santorum scored a distant third place with 13.34 percent of the vote, while Paul was fourth with 7.01 percent.
Meanwhile, real estate mogul Donald Trump said he would make a "major announcement" Thursday about the US presidential race, having earlier said that he would endorse a Republican candidate "in a very short period of time."