Commentary: Gerard Baker | Bill Clinton claims vote-rigging | McCain wins South Carolina

Hillary Clinton has won the Nevada caucuses, powering past Barack Obama in a race marred by allegations of dirty tricks and leaving her challenger badly needing victory in South Carolina next week.

Mrs Clinton's victory came with overwhelming support from older voters, women and the Silver State's Hispanic population, with the economy the dominant issue, compared to support for Mr Obama among young people and the state's black community.

Mitt Romney won Nevada's Republican caucus, but it terms of his party's overall race, it will have little impact. Most of his rivals ignored Nevada to focus on today's contest in South Carolina. Mr Romney was the only Republican to campaign in Nevada this week.

The victory marks a second win for Mrs Clinton after her triumph in New Hampshire last week. It leaves Mr Obama, who won the first contest in Iowa on January 3, under increasing pressure to win the South Carolina primary next Saturday, where half the Democratic electorate is African American.

Mrs Clinton won 51 per cent of the vote, with Mr Obama at 45 per cent and the former North Carolina Senator John Edwards placing a distant third on 4 per cent. Mr Edwards vowed to carry on, but after losses in Iowa, New Hampshire and Nevada his campaign is now on life-support.

"I guess this is how the West was won," Mrs Clinton declared, joined on stage at a victory rally with her husband Bill and daughter Chelsea.

The former First Lady, referring to a bruising Nevada, said: "We will all be united in November," she said, as the crowd chanted "H-R-C! H-R-C!"

The demographics of Mrs Clinton's win in Nevada – with support from women, Hispanics, people over 45 and voters with financial concerns – is reflected nationally. Her aides believe such backing could decisively tip the nomination battle in her favour on February 5, "Super Tuesday", when 22 states vote, including the delegate-rich prizes on California, and New York, the state she represents in the Senate.

The Obama campaign tried to undermine Mrs Clinton's victory. It claimed that under the complicated mathematics of the caucus system it had actually been awarded more Nevada delegates than Mrs Clinton - because it won more rural areas - despite her overall six-point win.

“We ran an honest, uplifting campaign in Nevada that focused on the real problems Americans are facing, a campaign that appealed to people’s hopes instead of their fears. That’s the campaign we’ll take to South Carolina and across America in the weeks to come, and that’s how we will truly bring about the change this country is hungry for.”

A senior aide to Mr Obama claimed dirty tricks, saying: “We currently have reports of over 200 separate incidents of trouble at caucus sites.”

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