Mitt Romney scored his third major victory in the Republican presidential race in Nevada Saturday, easily outpolling runnerup Newt Gingrich.

Romney, the former Massachusetts governor, held a double-digit lead over Gingrich, the former House speaker, as the totals mounted late Saturday night in a state where fellow Mormons accounted for roughly a quarter of all caucus-goers.

Gingrich and Texas Rep. Ron Paul vied for a distant second. Former Pennsylvania senator Rick Santorum trailed the field. Returns from 14 of 17 counties showed Romney with 42 per cent support, Gingrich with 25 per cent, Paul with 20 per cent and Santorum with 13 per cent.

At a Las Vegas news conference following the vote, Gingrich swatted aside any talk of a withdrawal and emphatically renewed an earlier vow to campaign into the party convention in Tampa, Fla., this summer. He said his goal was to "find a series of victories, which by the end of Texas primary will leave us at parity" with Romney by early April.

Rough road

Gingrich has had a rough road on the campaign trail since his resounding loss to Romney in Florida following a US $14 million barrage of negative advertising launched against him by pro-Romney forces.

Gingrich's campaign suggested to reporters all week that real estate mogul Donald Trump was about to endorse him; in fact, the mega-mouthed millionaire threw his support behind the former Massachusetts governor on Thursday.

Gingrich also reportedly missed a meeting with Brian Sandoval, governor of Nevada. Sandoval supported Texas Gov. Rick Perry's run for president and was thought to be ready to back Gingrich.

Nonetheless, Gingrich handlers have high hopes for so-called Super Tuesday, a day of multiple caucuses and primaries on March 6. The delegate-rich state of Georgia, in particular, could be fertile ground for Gingrich.

The winning candidate has to win 1,144 delegates to get the nomination. Victories in the early primaries and caucuses generally propel a winning candidate to the later states on a wave of momentum.

Romney's already taken New Hampshire, Florida and now Nevada.

It's the second time he's won Nevada — four years ago, during his first run for president, he took the state with 51 per cent of the vote.