US Republican presidential hopeful Newt Gingrich hopes a 'Super Tuesday' vote bonanza in March will rescue his faltering campaign after a second consecutive thumping from rival Mitt Romney.
Gingrich trailed in Nevada by a massive 25-per cent margin with almost three-quarters of precincts reporting -- a second big loss within five days that raised questions about the viability of his longer-term challenge.
Speaking on two Sunday morning talk shows, the candidate put a brave face on the defeat and insisted things would be different in a month's time when 10 states votes at once and almost a fifth of all delegates are decided.
'Our goal is to get to Super Tuesday, where we're in much more favourable territory,' Gingrich said on NBC's Meet the Press, adding that he expects to do much better in conservative southern states like Georgia and Alabama.
Gingrich, a 68-year-old former House speaker, has vowed a long game in the state-by-state voting battle for the Republican nomination, where 2,286 delegates are at stake and a candidate must accumulate 1,144 votes to win.
The Republican establishment hopes the contest will be over well before the August 27-31 convention in Tampa, Florida, avoiding a bitter battle that could hurt the eventual nominee's chances against Democratic President Barack Obama.
Romney's Nevada victory followed a resounding win in Florida, and the multi-millionaire former venture capitalist and Massachusetts governor is now the clear frontrunner to be taking on Obama in November's general election.
That said, there are 437 delegates up for grabs on 'Super Tuesday' -- by contrast, Nevada awarded only 28 and Florida 50.
'This does not by any means end the nomination race,' Harvard University political expert Elaine Kamarck told AFP.
'Two things end nomination races,' she said. 'One, a candidate runs out of money. This year, because of the Supreme Court decision that effectively allows for lots of money in campaigns, no one seems to be running out of money.
'Two, one candidate reaches the magic number of delegates to win the nomination in Tampa. That is not likely to happen until April. So I see a long race unfolding until one of the two above situations happens.'
Thanks to the Citizens United ruling Kamarck was referring to, candidates can receive unlimited corporate donations to so-called Super PACS, political action committees that are ostensibly -- but not really -- independent.
Gingrich has received substantial funding from billionaire casino mogul Sheldon Adelson and his wife Miriam -- to the tune of $US10 million ($A9.33 million) during the recent South Carolina and Florida campaigns, according to media reports.
Asked if Gingrich could last beyond Super Tuesday, University of Virginia's Larry Sabato said: 'You should ask Mr Adelson because if the Super PAC money is ever cut off, that will probably be the end of Gingrich's campaign.
'We're in a new era, when one or two financial angels can literally continue or end a campaign,' he told AFP.
But, for Sabato at least, Romney will be the eventual winner.
'It's already inevitable. It's over, but it takes a while for these things to play out. There is no one else who has the ability to run a national campaign and win.'
Nevada residents voted on Saturday. With 71 per cent of ballots counted, Romney had 48 per cent of the vote -- a decisive lead, although below the 50 per cent he earned in his 2008 presidential run.
Gingrich trailed with 23 per cent, Texas representative Ron Paul was third with 18 per cent, followed by Christian conservative Rick Santorum, a former US senator from Pennsylvania, with 11 per cent.
In his victory speech, Romney failed to mention a single one of his Republican rivals, training his attacks solely on Obama -- in a clear sign that he wants to reassert his above-the-fray frontrunner status.
'This president's misguided policies made these tough times last longer,' he said. 'America needs a president who can fix the economy because he understands the economy, and I do, and I will.'
Romney's win in the Silver State -- helped by a large Mormon community which shares his faith -- was his third victory over Gingrich, after New Hampshire and Florida. Santorum pipped Romney by a handful of votes in Iowa.
Gingrich shocked the party establishment when he thumped Romney, 64, in South Carolina in mid-January, but his support has since flagged.
