Clinton and Obama dig in for long fight after Super Tuesday

But, on a night when the two Democratic rivals traded blow for blow in an tight and unprecedented coast-to-coast fight for delegates, Mr Obama picked up at least 13 states – often by convincing margins.

He strolled to victories in the Southern states of Georgia and Alabama, as well as Kansas, Delaware, his home state of Illinois, North Dakota, Minnesota, Idaho, Utah, Colorado, Connecticut, Missouri and Alaska.

Nationally, Mrs Clinton had the edge among women, Hispanics and older voters. Mr Obama won overwhelming majorities among black voters and younger people, as well as a smaller majority among white males.

In the Republican race, John McCain secured a raft of anticipated victories in early Super Tuesday contests across delegate-rich New York, Illinois, Missouri and New Jersey, before landing California – and setting himself firmly on course for the nomination.

He told a crowd in Phoenix, Arizona that after being an underdog for months: “We should now get used to the idea that we are now the Republican party frontrunner for the nomination”. As his words were drowned out by cheers, he added: “And I don’t really mind it one bit.”

It was announced today that Mr McCain will meet Gordon Brown during a visit to London on Friday, although the Prime Minister’s office denied that the meeting amounted to an endorsement of the 71-year-old senator.

Mitt Romney defiantly promised to fight on, despite picking up only a handful of states including Massachusetts, where he was once governor, and Utah, dominated by fellow Mormons.

He was hit hard by Mike Huckabee who split the social conservative vote and picked up five states of his own.

Mrs Clinton, speaking in Manhattan to supporters who appeared jubilant even before the California result, adopted some of Mr Obama’s language of unity, saying: “Tonight we’re hearing the voices of people across America - people of all ages, of all races, all faiths and all walks of life.”

But she also highlighted what is regarded as her strength in a looming general election contest, saying she would not waver in the face of the kind of tactics which smeared the war record of Democrat nominee John Kerry during the last presidential race.

“We know that the Republicans will not give up the White House without a fight. I will not let anyone Swift Boat this country’s future. Together, we can take back America.”

Mr Obama, addressing an equally boisterous crowd in Chicago, said: “There is one thing on this February night that we don’t need the final results to know: Our time has come.”

While professing respect and friendship for Mrs Clinton, he said: “We owe the American people a real choice. We have to choose between change and more of the same, we have to choose between looking backwards and looking forwards, we have to choose between our future and the our past.” He suggested that if his rival won the nomination, Democrats would go into a general election “with half the country already united against us”.

For all the headline victories last night, Super Tuesday has done little to clarify who will win the Democratic contest because party rules stipulate that delegates in most states must be awarded proportionately. This means neither Mr Obama nor Mrs Clinton expect to emerge from last night’s results with a decisive advantage over the other in terms of delegates.

Instead, there was an immediate battle for interpretation of results. The Clinton campaign issued a stream of “talking point” memos, emphasising that her wins in Oklahoma and Tennessee contradicted Mr Obama’s claims that he “had a monopoly” on Republican-leaning states.

Her victory in Massachusetts was described as “one of the biggest surprises of the night”.

While Mr Obama’s overwhelming support among black voters propelled him to victory in Georgia and Alabama, Mrs Clinton appeared to be splitting with him much of the white vote which might otherwise have gone to John Edwards, who dropped out of the race last week.

Howard Wolfson, her communications chief, said: “This has been a strong night but the contest will continue long into the future through the February states into the March 4 contests and in all likelihood beyond.”

David Alexrod, Mr Obama’s chief strategist, speaking in Chicago, said: “Both campaigns are coming out with a roughly even delegate count. It is a phenomenal thing when you think where we were a month and a half ago, when we were the prohibitive underdog against the biggest name in Democratic politics. To fight them to a draw, coast-to-coast...this is a real achievement and speaks to the power of his candidacy.”

The rival campaigns are already turning their focus to fresh battles in six states over the next week – or even further ahead to critical contests in delegate-rich Ohio and Texas on March 4 – as well to the Pennsylvania primary on April 22.

This weekend, the focus shifts to Nebraska, Louisiana, Washington State and the Virgin Islands, with a total of 204 delegates on offer. Next Tuesday is the “Potomac Primary” – contests in Washington DC, Virginia and Maryland – where Mr Obama is expected to do well because of the heavy number of black Democratic voters.

Mrs Clinton threw down the gauntlet to Mr Obama for head-to-head duels in no less than four televised debates this month. Her campaign said this would allow voters to see how the candidates measure up “side by side” rather than rely on the “rallies and big events” favoured by Mr Obama where statements go “unchallenged”.

Mr Obama’s campaign manager, David Plouffe, said: “We have done 18 debates. Our schedule will not be determined by the Clinton camp. We’re going to evaluate our schedule and debates will be part of it.”

Mrs Clinton’s aides insisted that her decision to accept the debates including two in the next five days and one from the Fox TV – a channel often viewed with suspicion by Democrats - did not mean she was now the underdog candidate trying to snatch back the spotlight.

Instead, they said she wanted to demonstrate - as she has done in the past - that she makes an “effective case”. Her campaign believe Mr Obama has recently been getting a free ride from a largely uncritical media.

The prospect of a damaging drawn out fight running even up to the convention in August is beginning to alarm Democrats, seven in ten of whom - according to exit polls last night - would be content with either Mrs Clinton or Mr Obama as the nominee.

Howard Dean, the chairman of the Democratic National Committee, said that a “convention battle would be a problem”. He pointed out that the previous three divided conventions in 1968, 1972 and 1980 had all resulted in the election of a Republican president.

Critical for both candidates are the 796 “superdelegates”, the Democratic Party’s senators, congressman and congresswomen, state governors, former presidents and senior officials, who are not bound by the results of the primaries and caucuses. Mrs Clinton and Mr Obama are lobbying them furiously, making telephone calls and sending emails to try to gain their support.

Wins - Democrat

Obama - North Dakota, Alabama , Kansas, Delaware, Illinois, Georgia, Connecticut, Minnesota, Colorado, Idaho, Missouri, Alaska, Utah

Clinton - California, New Jersey, Massachusetts, New York, Oklahoma, Arkansas, Tennessee, Arizona, American Samoa

Wins - Republicans

McCain - California, Arizona, Oklahoma, New York, Delaware, Connecticut, Illinois, New Jersey, MIssouri

Romney - Utah, Massachusetts, North Dakota, Minnesota, Montana, Alaska, Colorado

Huckabee - West Virginia, Arkansas, Alabama, Georgia, Tennessee