With support from a broad cross-section of Republicans, Romney won by a big double-digit margin over former US House Speaker Newt Gingrich, Representative Ron Paul and former Senator Rick Santorum.
The victory was Romney's second in a row and his third in the first five contests in the state-by-state battle to find a Republican challenger to President Barack Obama in November's general election.
It propels Romney into the next contests — in Minnesota, Colorado and Missouri on Tuesday — on a growing wave of momentum.
Gingrich held a news conference after the results to head off speculation that he might put an early end to his campaign.
"I'm not going to withdraw," Gingrich told reporters, repeating his frequent vow to continue all the way to the Republican nominating convention in Florida in August. "I'm actually pretty happy with where we are." Romney, a former Massachusetts governor, took control of the Nevada contest early after recapturing his front-runner status with a convincing win over Gingrich in Florida last Tuesday.
He benefited from a huge financial and organizational edge in Nevada, which he won with 51 percent of the vote during his failed 2008 presidential bid. A faltering economy and a big bloc of Mormon voters made Nevada friendly terrain for Romney, a Mormon and former head of a private equity firm.
Romney stressed his business background as a cure for the state's ailing economy, which suffers from the country's highest unemployment rate, 12.6 percent in December, and the highest home foreclosure rate.
Entrance polls in Nevada showed that was a persuasive argument, with the economy ranking as the top issue and Romney winning nearly two-thirds of the voters who listed it as their biggest concern.
"America needs a president who can fix the economy because he understands the economy, and I do and I will," Romney told cheering supporters at a Las Vegas casino hotel, aiming his criticism at Obama and ignoring his Republican rivals.
The entrance polls showed Romney won a broad swath of voters, including moderates, conservatives, men, women, the elderly, Tea Party supporters and those who believed the most important quality in a candidate was the ability to beat Obama.
Romney hopes Nevada will kick off a February winning streak that could position him for a knockout blow to Gingrich during the 10 "Super Tuesday" contests on March 6 — or sooner.
In addition to Tuesday's contests, Maine will wrap up its weeklong caucuses next Saturday, while Arizona and Michigan hold their contests on Feb. 28.
Romney won Colorado, Minnesota, Maine and Michigan in 2008. He came in second in Arizona to native son and eventual nominee John McCain, an Arizona senator. He finished third in Missouri.
Gingrich hopes to hang in the race until March, when there will be contests in several southern states where the former Georgia congressman believes he can do well. He said his goal was to pull even with Romney in delegates after the Texas contest in early April.
Gingrich campaigned in Nevada but did not spend any money on advertising in the state. Paul, who is focusing on Nevada and other caucus states, spent on advertising and voter turnout efforts in the state.
Santorum, who finished a distant fourth in Nevada, skipped the state entirely. He said the race would begin to shift as it moved past the first five states, where Romney had an organizational advantage.
"We think this is an opportunity for us to begin to turn this race," he told CNN. "The more this race goes on, the more people see we present the best chance to win this."
At least 1,144 delegates are needed to secure the nomination in August. Nevada will award 28 delegates and split them proportionally based on the vote total Nevada's caucuses were held at 125 sites around the state, with voters breaking up into small groups by precinct to tout their candidates and debate their choices. Several Romney supporters said they backed him because he could win in November.
"I think he's the only one who can beat Obama," said George Peterson, a retired Air Force veteran who attended a caucus at Chaparral High School in Las Vegas.
Gayle Darin, an executive assistant at the Bellagio hotel, said she thought it was time for Republicans to pick a candidate and begin to focus on Obama.
"A lot of people have rallied behind Romney now," she said. "We've got to step up and get Obama out of office." Romney and Gingrich both plan to take a day off the campaign trail on Sunday.
