US:Democrats caucus in Nevada today as Republicans vote in South Carolina in contests that are too close to call on both sides, as campaigns dig in for a race that could remain undecided even after Super Tuesday on February 5th.
Barack Obama goes into the Nevada caucus as favourite after a court threw out a challenge by Hillary Clinton's supporters to a plan to allow casino workers to caucus at venues on the Las Vegas strip. The Culinary Workers Union, which represents more than 60,000 hotel and casino workers, has endorsed Mr Obama, although Mrs Clinton and former senator John Edwards have received the support of smaller unions.
Most Republican candidates are ignoring their party's Nevada caucus and focusing instead on South Carolina, the first southern state to vote and traditionally a crucial test for Republican candidates.
A new poll puts Arizona senator John McCain neck and neck with former Arkansas governor Mike Huckabee, with 27 per cent and 25 per cent respectively. The McClatchy/MSNBC poll puts former Massachusetts governor Mitt Romney in third place with 15 per cent, followed by former Tennessee senator Fred Thompson at 13 per cent.
Mr McCain lost South Carolina to George W Bush in 2000 after a dirty tricks campaign that included anonymous phone calls claiming that the Arizona senator had fathered a child out of wedlock. Mr McCain has faced more dirty tricks this time, with a group of Vietnam veterans questioning his war record and claiming falsely that he betrayed his comrades while in captivity in Hanoi for five years.
"A lot of nasty things are going on," Mr McCain said this week.
To counter such attacks this year, the McCain campaign has formed a "truth squad" of four high-level Republican state officials, who are acting as a rapid-response team against misleading information.
"We've learned from experience. We know what happened here in 2000 and we felt it was very important to be prepared if the campaign did take a negative turn," said BJ Boling, Mr McCain's communications director in the state.
Mr McCain, who won in New Hampshire last week but lost to Mr Romney in Michigan on Tuesday, needs a victory in South Carolina to sustain momentum and keep campaign contributions coming in. Ahead in national polls, Mr McCain hopes a win in South Carolina will help him defeat former New York mayor Rudy Giuliani in Florida on January 29th and go on to victory on Super Tuesday a week later.
Mr Huckabee, who won in Iowa but came third in New Hampshire and Michigan, hopes that his appeal to evangelical Christians will bring him victory in South Carolina. He has courted social conservatives aggressively in the past week, comparing gay marriage to bestiality and floating the idea of an amendment to bring the US constitution more into line with Christian principles.
Mr McCain, who alienated many voters in Michigan by telling them bluntly that lost manufacturing jobs might not return to the state, has sounded more upbeat in South Carolina, promising cuts in tax and government spending to revive the US economy.
In Nevada, Mrs Clinton hopes that a renewed focus on the economy could give her an upset victory and she has run radio adverts claiming that Mr Obama has links to financial backers of a controversial nuclear waste disposal scheme at Yucca Mountain, outside Las Vegas.
At a campaign rally at a Las Vegas high school, Mr Obama poked fun at Mrs Clinton, presenting her as a candidate who will say anything to get elected.
He joked about her criticism of his answer to a question at this week's candidates' debate over each candidate's weakness, when Mr Obama mentioned his messy desk and said that he loses paper easily.
"So I thought, you know, because I'm like an ordinary person, I thought that they meant 'what's your biggest weakness?' " he said.
"And so the other two they say, they say well my biggest weakness is, 'I'm just too passionate about helping poor people. I am just too impatient to bring about change in America.' If I had gone last, I would have known what the game was. I could have said, 'Well you know, I like to help old ladies across the street. Sometimes they don't want to be helped. It's terrible.' "