Republican US presidential hopeful Mitt Romney looks set to romp to victory in the Nevada caucuses, cementing his position as frontrunner four days after his crushing Florida win.
Voting got underway under clear blue skies in the Silver State with Romney holding a big lead in polls as he and rival candidates prepared to head to the next nominating contest in Colorado, another Western state.
Mr Romney has shrugged off a wobble this week with a gaffe about America's poor: the former Massachusetts governor has a huge lead in Nevada of 50% against 25% for Mr Gingrich, according to an eve-of-caucus poll.
But there is no sign that any of his three opponents, led by Mr Gingrich, plan to throw in the towel.
Mr Romney is expected to repeat his triumph here of four years ago, helped by strong backing from fellow Mormons which could see him consign nearest rival Gingrich to a distant second place. Voting will close at 11pm Irish time.
"Everybody knows he's going to win, it's about how big he wins, and how much of the vote he gets," said David Damore, Associate Professor of Politics at the University of Nevada, Las Vegas.
"They're basically competing against expectations now: can he do better than 50%, which is about what he got four years ago?"
Mr Gingrich, who turned the Republican race for the White House on its head with a big win in the South Carolina primary last month, is struggling to regain momentum after a heavy loss to Romney in Florida on Tuesday.
Nevada is the first western US state to take part in the nominating contest which will eventually select the Republican Party's challenger for the November elections against Democratic President Barack Obama.
Mr Romney is aiming for a third victory over Gingrich, after New Hampshire and Florida, and he seems to have dampened a row that broke out after he said he was "not concerned" about "very poor" Americans.
He insisted the context of his comments showed he was concerned about all Americans, but his focus is on middle class voters who have been worst hit by a recession and sluggish US recovery after the 2008 global downturn.
The remarks about the poor sparked new accusations that the wealthy former venture capitalist, who lives off the returns made on his investments, is out of touch with ordinary voters.
Mr Gingrich in an eve-of-caucus rally in Las Vegas renewed his attacks on the frontrunner for the slip.
"Governor Romney is trying to recover from his boo boo," he said to laughter and whoops from supporters at a music bar in the desert gambling city.
Mr Romney also raised eyebrows after he released tax filings showing he earned $20m from his investments in 2010 and paid just 13.9% in taxes - a lower rate than many struggling Americans.
