Judge Allows Casino Sites for Nevada Caucuses

"The fact is their camp clearly would like to have worker's voices silenced and they need to live with that unfortunate position," Burton wrote.

Obama and Clinton also sparred on Thursday over the proposed Yucca Mountain nuclear waste site, a huge concern for voters here. Clinton hit both Obama and Edwards with a radio ad questioning the strength of their opposition to the site.

The ad noted that Edwards had previously supported the Nevada repository, while Obama had raised campaign funds from officials in the nuclear industry. The Obama campaign responded with statements and a hastily arranged conference call to underscore his consistent opposition to the Yucca site.

Edwards, fighting for his first win of the primary season, challenged remarks that Obama made about former president Ronald Reagan in an interview with the Reno Gazette-Journal. Obama, who has aggressively courted Republicans and independents, told the newspaper: "I think Ronald Reagan changed the trajectory of America in a way that Richard Nixon did not and in a way that Bill Clinton did not. He put us on a fundamentally different path because the country was ready for it."

In response, Edwards said that Reagan "did extraordinary damage to the middle class and working people, created a tax structure that favored the very wealthiest Americans and caused the middle class and working people to struggle every single day."

A poll by the Las Vegas Review-Journal, scheduled to be released today, is expected to show Clinton with a nine-point lead in the state, although turnout is considered such a wild card that not one of the campaigns is willing to predict the outcome. Republicans will also caucus Saturday, although only former Massachusetts governor Mitt Romney is making an aggressive play in the state.

The 2004 Nevada Democratic caucuses attracted fewer than 10,000 participants and took place after the nomination of John F. Kerry (D-Mass.) was virtually a done deal. This time, with its prominent early spot on the campaign calendar, the number could climb to 75,000, according to some of the campaigns.

Staff writer Matthew Mosk in Washington contributed to this report.