Republican John McCain and Democrat Hillary Clinton today looked towards the next battles in a see-saw race for their party's presidential nomination after scoring tough wins in the first voting in the South and West yesterday.
Mr McCain narrowly defeated rival Mike Huckabee in South Carolina - a state where Mr McCain's presidential hopes were destroyed in a bitter 2000 battle that set George W Bush on a path to the White House.
The Arizona senator, told cheering supporters in Charleston: "We are well on our way tonight."
His victory, which followed triumph in New Hampshire earlier this month, is all the more impressive considering exit polls showed he had support from conservatives.
Mr Huckabee, a former Arkansas governor and Baptist preacher won in Iowa thanks to religious support.
In Nevada's Democratic race, Ms Clinton beat Barack Obama in a close struggle that featured voting in the state's famed casino hotels and produced heated charges of irregularities.
The pair had split the first two Democratic contests. "I guess this is how the West was won," Ms Clinton said.
Mitt Romney, the former Massachusetts governor, won a Republican race in Nevada that his rivals largely skipped in order to concentrate on South Carolina.
Candidate in both parties have so far failed to claim the front-runner's role in the race to pick the candidates to contest the November 4th election to succeed Mr Bush.
The battle now turns to the deep South, where the next fights will be South Carolina's Democratic primary next Saturday and Florida's Republican primary on January 29th.
Then both parties turn their attention to the February 5th "Super Tuesday" round of 22 state contests.
Mr Obama, an Illinois senator who could be the first black US president, leads polls in South Carolina, where more than half of the primary voters are expected to be black.
Ms Clinton won the Nevada vote 51 per cent to 45 per cent over Mr Obama, with turnout in excess of 115,000. Former North Carolina Senator John Edwards finished a distant third.
"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," Mr Obama said.
The Florida Republican race will mark the debut of former New York Mayor Rudy Giuliani, who has seen his once substantial lead in national opinion polls disappear after effectively sitting out the first contests.
Mr Giuliani has gambled that a win in Florida will propel him to a strong showing on February 5th in populous states like New York, California, New Jersey and Illinois.
Mr McCain accepted the race is "very competitive" and highlighted the importance of the Florida primary. "I don't know if it's a must-win but it's certainly a very, very important race," he said.