Trump takes Nevada's Republican caucuses

The 69-year-old billionaire reality TV star trounced his Republican rivals with a resounding victory which sent shockwaves across the Grand Old Party (GOP) as he swept almost every category of the electorate to build his dominance in the delegate count.

Projections on TV networks gave Trump 46 per cent of the vote, with Senators Marco Rubio of Florida and Ted Cruz of Texas trailing some 20 points behind.

Turnout was high, exceeding all expectations, with some Caucus sites running low on ballots.

The remaining two candidates for the Republican presidential nomination, retired neurosurgeon Ben Carson and Ohio Governor John Kasich, came in at about six and four per cent, respectively.

"We will be celebrating for a long time tonight," Trump told cheering supporters in a victory speech.

"We were not expected to win too much and now we are winning the country. And soon the country is going to start winning, winning, winning," Trump told enthusiastic and cheering supporters.

Trump has now won three of the four early nominating states, after convincing wins in South Carolina and New Hampshire. He came second in Iowa Caucus which was won by Cruz.

The Republicans now look ahead to Super Tuesday on March 1 when 11 states are due to hold contests and could have a decisive impact on the Republican nomination for the White House. Trump's campaign hopes to take an unsurmountable lead over his nearest rivals in the Super Tuesday.

Referring to the recent opinion polls, he said "some great numbers are coming out of" Texas, Tennessee, Georgia, Arkansas, Florida.

"We are doing very well in Ohio. We are beating the Governor (John Kasich, who is a presidential candidate), and Michigan. It is going to be an amazing two months," he said referring to the calendar of the GOP's presidential race.

"We might not even need the two months, folks to be honest," Trump said in his brief victory speech wherein he took a dig at critics who have doubted his winnability.

"They keep protecting that when people drop out, we are going to get a lot of votes," Trump said as he reiterated his vision of making America great again.

"It is hard for me to turn down money, because that's what I have done my whole life...grab, grab and grab. I get greedy, I want money. Now I will tell you what I am going to do. Now we are going to get greedy for the United States, grab, grab and grab," he said.

Congratulating Trump on his victory, Cruz told supporters that he is the only Republican leader left in the race who can defeat Trump.