Rival fighters both claim a victory on points as they gear up for next round

Mr Obama proved the breadth of his national appeal and the strength of his campaign organisation by triumphing — often by convincing margins — in a swath of smaller contests as well as his home base in Illinois. He prevailed in tight fights in Missouri and Connecticut. Mrs Clinton took Massachusetts, where Senator Edward Kennedy had endorsed her rival.

Their differing appeals on lines of race, class and gender, in effect, cancelled each other out. Mr Obama again secured the bulk of black, young and higher-income liberal white voters. Mrs Clinton did well among older women, Latinos and working-class white Democrats. At the end of the night the two candidates had almost identical support in the number of votes cast and delegates won.

Both sides, inevitably, claimed to have momentum on their side. Mr Obama’s aides said their campaign was on a clear path to victory. He is raising dramatically more money than Mrs Clinton — collecting $32 million (£16 million) in January to her $12 million. Mrs Clinton’s spokesman confirmed yesterday that she had been forced to lend her campaign $5 million from her family’s own fortune, built by her husband’s lucrative speaking tourrs of his post-White House years.

Mr Obama believes the next seven contests should favour him. Four are in states with large proportions of black voters — Louisiana, Maryland, Virgina and Washington DC — while three more in Nebraska, Washington State and Maine — are caucuses, in which he has excelled because of his ground organisation.He won caucuses in Colorado, Kansas, Minnesota and North Dakota on Tuesday.

David Axelrod, his chief strategist, said that Mr Obama had climbed from behind in national and state-by-state polls, which Mrs Clinton had mostly led until very recently. “It is a phenomenal thing when you think where we were a month and a half ago. We were the underdog against the biggest name in Democratic politics,” he added.

David Plouffe, Mr Obama’s campaign manager, said: “This was day to get the upper hand in the nomination fight, and they most decidedly failed in that regard.”

Mark Penn, the strategist for Mrs Clinton, suggested that Mr Obama’s surge in the last week had been halted and that “momentum had turned” in the final hours before Super Tuesday. He said that she did best in contested states. “Where we fought and advertised, that was where we had our largest margins,”

Her campaign is setting its sights beyond the remaining contests this month and towards Ohio and Texas on March 4, as well as Pennsylvania on April 22, regions heavy with blue-collar and union households, or the Latino voters who supported her so strongly in California.

The different paths that these campaigns are cutting across America is a reflection of both the character and the beliefs of the candidates. Mr Obama focused on smaller, often Republican states, as well as those holding caucuses rather than primaries. He has sought to build a movement of activists, claiming that change does not come from the top down but when the grass roots are inspired to demand it.

Mrs Clinton concentrated her fire on the big states and mobilising a Democratic vote. She appears more at at ease as a national candidate, practising politics “wholesale” rather than the close-up, “retail” style of the early voting states.

She has challenged Mr Obama to four head-to-head televised debates this month. Her campaign said this would allow voters to see how the candidates measured up side by side rather than relying on the rallies and big events favoured by Mr Obama where statements went unchallenged. Mrs Clinton wants to demonstrate that she makes an “effective case”. Aides say that Mr Obama has been getting a free ride from an uncritical media.

The distinction between them was also apparent in speeches on Tuesday night to their respective groups of supporters. Mrs Clinton and Mr Obama both reprised their core messages which have increasingly been honed down to distinct visions on how to win the presidential election for the Democrats in November.

Addressing a rally in Manhattan that was exuberant even before the California result, Mrs Clinton asserted her tested durability for November’s looming contest, and said that she would not waver in the face of the kind of tactics that smeared the war record of the 2004 Democratic nominee, John Kerry.

“We know that the Republicans will not give up the White House without a fight,” she said. “Let me be very clear: I will not let anyone ‘swift boat’ this country’s future. Together, we can take back America.”

Mr Obama told his own boisterous rally in Chicago: “Our time has come, our movement is real, and change is coming to America.” He professed respect and friendship for Mrs Clinton but declared: “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 his rival was too polarising a figure to win the White House. “It’s a choice between going into this election with Republicans and independents already united against us, and going against their nominee with a campaign that has united Americans of all parties, of all backgrounds, of all races, of all religions, for a common purpose.”

It was significant that both candidates tried to make encroachments on the other’s territory. Mrs Clinton adopted some of Mr Obama’s language of unity and change, 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. I look forward to continuing our campaign and our debate about how to leave this country better off for the next generation.”

Mr Penn suggested yesterday that Mr Obama had suffered on Tuesday for deciding to run an “Establishment-orientated campaign” which had relied heavily on endorsements from the likes of Senator Kennedy in Massachusetts and the Governor of Arizona, Janet Napolitano, who command significant political machines.

He claimed that Mrs Clinton’s victory in both states showed voters preferred her “substance-orientated campaign” which has in recent days focused strongly on issues such as health care, the economy and her credentials as a commander-in-chief.

Mr Obama, at an airport press conference yesterday, dismissed the implication that he was not tough enough to stand up to the Republican attack machine, saying recent scraps with Mrs Clinton had proven “we can take a punch and we’re still standing”. Hinting that successive scandals in the 1990s could prevent a Clinton restoration to the White House if she was the Democratic nominee, he said: “The notion that somehow Senator Clinton is going to be immune from attack or that there is not a whole dump truck they can’t back up in a contest against John McCain is just not true.”

Neither side expects the battle to end soon. Democratic party rules require delegates to be awarded proportionately in each state. Mr Penn said : “It will be very hard to amass a large delegate lead.”

He suggested that those who wanted an old-fashioned brokered convention might get their wish. “This is going to be a neck-and-neck contest for the foreseeable future.” The prospect of a damaging drawn-out fight running even up to the convention in Denver this August is beginning to alarm Democrats, seven in ten of whom — according to exit polls on Tuesday — would be content with either Mrs Clinton or Mr Obama as the nominee.

Howard Dean, the chairman of the Democratic National Committee, acknowledged that 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.

The bloggers’ view

“A woman might have a different perspective on how to deal with our international relationships”
Margaret Bramble, 38 (Her husband also voted Clinton: “Since I am the one with the degree in political science, he usually listens to me”)

“With Hillary in there, even if she screws up, Bill will be there”
James Sims, 34

“Obama really represents the restart of our country. I want to turn it off and start it up again”
Josh Koppel, 33

“People voting for Obama are full of cheer. I believe he’s gonna help spread the wealth, but he’s a stern dude and he’s gonna make people work for the money”
Curtis Bolden, 30

“I know he is not going to win, but his name is still on the ballot. John Edwards had the most comprehensive healthcare plan, but people were only concerned about his $400 haircuts”
Helen Ladoucey, 87