LAS VEGAS: Propelled again by women, with newfound support from Latinos, Hillary Clinton won the vote in the boisterous, quirky Nevada caucuses on Saturday, giving her fresh momentum in the battle for South Carolina next Saturday and for 22 states three days later.

Voters flocked to polling places statewide, including at casinos and hotels on the Strip where hat-wearing chefs and card dealers helped deliver a win in the overall vote for Clinton, although the contest over delegates was far closer.

The state party said more than 115,000 people had participated in the Democratic caucuses, about half as many as in Iowa earlier this month.

Clinton took 51 per cent of the vote, followed by Barack Obama with 45 per cent. Former senator John Edwards of North Carolina trailed with less than 4 per cent.

Clinton's second win over Obama gives her campaign a shot of energy ahead of South Carolina's Democratic primary next weekend, leading into "Super Tuesday" on February 5 when 22 states will vote in Democratic contests.

At a brief news conference, the New York senator said she was not concerned about having done poorly among Nevada's African-Americans, as she heads to South Carolina where about half of Democratic primary voters are black.

"I'm going to work as hard as I can to reach out ... to every single voter," she said, adding that she won "a significant share of the popular vote" in Nevada.

But there was a complication when the Obama campaign announced he had edged out Clinton to get an estimated 13 out of the 25 national delegates who will eventually vote on the nomination at the Democratic National Convention in August.

Clinton campaign's denied that suggestion in a terse statement: "Hillary Clinton won the Nevada caucuses today by winning a majority of the delegates at stake. The Obama campaign is wrong."

The state party tried to clarify the result in a statement: "What were awarded today were delegates to the County Convention, of which Senator Clinton won the majority. No national convention delegates were awarded. That said, if the delegate preferences remain unchanged between now and April 2008, the calculations of national convention delegates (made by the Obama campaign) are correct."

The national delegates whom Obama has claimed in Nevada won't be selected officially until a state convention in April, but the county delegates elected on Saturday have pledged to elect delegates to the state convention, which should give Obama the victory he claims.

If that wasn't confusing enough, delegates at every level can change their minds.

Entrance polls showed Clinton took a large portion of women voters, just as she had in New Hampshire.

Almost six in 10 voters were women, and among them she held a 13-point margin.

She was evenly matched with Obama among men but Obama took 83 per cent of black voters - a statistic that bodes well for his prospects in South Carolina where blacks make up a large part of the party's base.

Clinton took almost three-quarters of the Hispanic vote, in a good sign for February 5.

Obama's campaign manager David Plouffe claimed "a lot of reports of irregularities" at caucus sites, such as a lack of registration forms, early caucus location closings and voter-identification issues.

"We want to get to the bottom of that," he said.

Obama received a big boost just 10 days before the caucuses when the 60,000-member Culinary Workers Union of Nevada endorsed him and offered free help on the ground.

On Thursday, a federal judge ruled nine "at-large" caucus locations in casinos or hotels on or near the Strip, thought to favour Obama, should stay open. But even at those locations, Clinton managed to stay about even with Obama.

At the Wynn Las Vegas casino, she won support from 189 compared with 187 for Obama. Down the Strip at the Luxor Hotel, Obama won 211 compared with 162 for Clinton.

In a Luxor ballroom, nearly 400 people - almost all African-Americans and Latinos - voted after hearing instructions in English and Spanish.

The Wynn casino ballroom was filled with white chef uniforms and brown maids dresses. Verbal jousting was spirited, as partisans waved posters for their candidates in the face of opponents.

Many culinary workers there were supporting Clinton, despite their union's endorsement of Obama. Some carried posters: "I support my union. I support Hillary."

Meanwhile, former Massachusetts governor Mitt Romney easily won Nevada's Republican vote. The wealthy former venture capitalist had no serious competition, after the other top-tier Republican candidates spurned the western desert state in favour of the South Carolina primary.