( dpa ) - A federal judge on Thursday gave the green light to hold voting in Saturday's Democratic primaries in nine casino hotels along the Las Vegas strip in a move that could swing the tight race towards Senator Barack Obama.
Obama has won the endorsement of the Culinary Workers' Union in his bid for the Democratic nomination for president. The union's members run the hotels that are at the heart of the Nevada economy.
Supporters of chief rival opponent Senator Hillary Clinton had appealed to the court to ban the hotel voting, arguing that allowing the workers to vote at their place of employment violated the equal access laws of the US constitution.
But Judge James Mahan of the US District Court for Nevada said that the Democrats were free to decide their own rules and rejected their request for an injunction.
"The Democrats can set up their own rules just as the Republicans can," the judge said. "It is not up to some federal judge to come along and say, 'I don't like that'."
Mahan even took a swipe at the Democratic Party's history of internal battling, quoting US humorist Will Rogers: "I'm not a member of any organized group. I'm a Democrat."
Obama welcomed the ruling.
"I think the judge was clear that you can't change the rules six days before the caucus, and any alterations would have disenfranchised the maids, dishwashers, bellhops who work on the Strip," he said in San Francisco.
Although the state is small, the Nevada vote will be closely watched for performance by the large Hispanic community. Republicans will also be caucusing in Nevada on Saturday, in addition to a single-party vote in South Carolina.
Democrats will vote on January 26 in South Carolina to choose their preferred presidential candidate.
Clinton holds a slight edge over Obama in national polling among Democrats. The race is wide open among Republicans, with three different candidates - former governors Mike Huckabee and Mitt Romney and Senator John McCain - winning in separate state primaries in Iowa, Michigan and New Hampshire respectively.
February 5 is the key date in the primary calendar, when 23 states will go to the polls on one day.