Mr Giuliani (left), a former front-runner whose candidacy collapsed quickly once the primaries and caucuses began, endorsed Mr McCain in glowing terms. -- PHOTO: AFP

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John McCain emerged as the clear front-runner for the Republican presidential nomination with a victory over former Massachusetts governor Mitt Romney in the hotly contested Florida primary on Tuesday. The veteran Arizona senator won a quick endorsement from Mr Giuliani before national contests on Feb 5, a series of 21 contests that could cement the White House nomination for the Republicans.

Mr Edwards' withdrawal turns the heated Democratic contest into a battle between Barack Obama and Hillary Rodham Clinton, who won a largely symbolic victory in Florida. No Democratic delegates were at stake and no candidates campaigned there because of a dispute between the state and national parties over the date of the primary.

'Step aside'
Speaking to a crowd in New Orleans on Wednesday, Mr Edwards said it was time to 'step aside so that history can blaze its path' in the race between a black man and a woman for the White House.

'With our convictions and a little backbone we will take back the White House in November' from the Republicans, he said.

The former North Carolina senator had lost the previous four state contests, unable to overcome the star power of Senator Obama and Mrs Clinton.

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The impact of Mr Edwards' decision will be felt in one week's time, when Democrats hold primaries and caucuses across 22 states, with 1,681 delegates at stake. Four in 10 Edwards supporters said their second choice in the race is Mrs Clinton, while a quarter prefer Senator Obama, according to an Associated Press-Yahoo poll conducted late this month.

Mr Edwards' withdrawal adds six of Edwards' delegates for Senator Obama, giving him a total of 187, and four more for Mrs Clinton, giving her 253. A total of 2,025 delegates are needed to secure the Democratic nomination.

Republican front-runner: McCain
Mr Giuliani, a former front-runner whose candidacy collapsed quickly once the primaries and caucuses began, endorsed Mr McCain in glowing terms. The Arizona senator 'is the most qualified candidate to be the next commander in chief of the United States. He is an American hero,' Mr Giuliani said with Mr McCain at his side in California.

Mr Giuliani finished a distant third in Florida on Tuesday after pinning all his hopes on the state and its community of retired New Yorkers.

Mr McCain's victory in Florida was worth 57 Republican National Convention delegates, a winner-take-all haul that catapulted him ahead of Mr Romney for the overall delegate lead.

More than 1,000 Republican delegates will be awarded on Feb 5 in 21 primaries and caucuses. A total of 1,191 delegates are needed to secure the nomination at this summer's Republican national convention.

Mr McCain, a former Vietnam prisoner-of-war, had been the early front-runner in the race only to see his campaign largely collapse last year. He rebounded with a coveted New Hampshire primary win on the back of support from independents. Still, many of the party's core conservative base remain wary of him, considering him too much of a maverick.

But with his victory in Florida, there were signs Mr McCain may be breaking through as the choice of the party establishment and a candidate able to unite all wings of the Republican Party. If so, he may be unstoppable.

Mr Giuliani's exit could help Mr McCain in more moderate delegate-rich states slated to vote next week, like California, New York and Illinois. But it also could give Romney fodder to claim that Mr McCain is not the truest conservative in the race, because Mr Giuliani is seen as liberal on social issues.

Gov Arnold Schwarzenegger to endorse McCain
Gov Arnold Schwarzenegger will endorse Sen John McCain on Thursday, giving a certain boost to the Republican presidential front-runner six days before California's high-prize primary.

The two will appear at a news conference after touring a Los Angeles-based solar energy company and the governor will make his endorsement official, his senior aides confirmed Wednesday.

Gov Schwarzenegger's move comes as Mr McCain plows ahead toward the nomination, the only Republican candidate to have won three hotly contested primaries since voting began earlier this month.

'Governor Schwarzenegger is an exceptional governor and we are honoured that he has decided to endorse Senator McCain, and look forward to the event tomorrow,' said Mr Steve Schmidt, a senior McCain advisor who managed Gov Schwarzenegger's 2006 campaign.

Disappointed Romney
A disappointed Mr Romney promised to press on after his second place finish following a tough Florida battle in which he traded insults and accusations with Mr McCain. He said Wednesday that Mr McCain may not be conservative enough to win the nomination.

'I think what will happen across the country is that conservatives will give a good thought to whether or not they want to hand the party's nomination over to Senator McCain,' Mr Romney said on ABC's 'Good Morning America.'

Mr Romney needed a strong showing in Wednesday night's Republican debate in California to put the brakes on Mr McCain's march to the nomination.

Among the others, Mike Huckabee, the former Arkansas governor and Baptist preacher who won Iowa, remains in the race, but has little money and finished a distant fourth in Florida. He could however split the conservative vote with his strong support among the religious right, a possible boost for Mr McCain.

Texas Representative Ron Paul has made no move to withdraw even though he scores in single digits in voting.

Mrs Clinton, locked in a tight race with Senator Obama, looked at her wide margin of victory in Florida to boost her campaign ahead of 'Super Tuesday,' in which 1,600 delegates are at stake. A total of 2,025 delegates are needed to secure the Democratic nomination at the party's convention in August.

But party rules alone make it unlikely that either one will emerge from next Tuesday with a commanding lead in the race for delegates. Unlike the Republicans, Democrats do not permit winner-take-all races.

Campaigning in Denver, Senator Obama elevated Mr McCain as the likely Republican nominee and depicted Mrs Clinton as a calculating, poll-tested divisive figure who will inspire greater partisan divisions as she sides with Republicans on issues like trade, the role of lobbyists in politics and national security. He depicted himself as he clear contrast to the rival party.

At a campaign stop in Arkansas, where her husband, former President Bill Clinton, was governor, Mrs Clinton proposed more protections for credit card users. -- AP