Hillary Clinton was left clinging to a cliff edge yesterday, with a senior ally reading the death rites over her presidential bid as the campaign confirmed that she had now staked much of her personal fortune on keeping it alive.

Barack Obama’s resounding 14-point victory in North Carolina on Tuesday night effectively ended her lingering chances of achieving a “game-changing” result that would have cut into his three-figure lead among elected delegates for the Democratic nomination. Although Mrs Clinton prevailed in Indiana, her razor-thin margin was less than might have been expected after the controversies that have dogged her rival over the past fortnight.

George McGovern, the Democratic presidential nominee in 1972, who had been an early backer of Mrs Clinton, called on her to drop out of a race that he believes is now virtually impossible to win. “The time has come for Democrats to unite and get ready for a tough race this fall against Senator McCain,” he said, explaining his decision to switch support to Mr Obama.

At a press conference in West Virginia, a defiant Mrs Clinton said: “I am staying in this race until there is a nominee. I believe I’m the strongest candidate against John McCain and believe I will be the best president among the three of us running.”

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Aides disclosed that Mrs Clinton had been forced to lend her debt-laden campaign another $6.4 million (£3.2 million) last month, on top of the $5 million she lent it in January. Howard Wolfson, her spokesman, said that this was roughly the same amount she had earned through book sales and her Senate salary — although he did not rule out her tapping into the much-larger fortune amassed by Bill Clinton since he left the White House.

Her campaign had already burnt through $157 million before the end of March and has increasingly struggled to keep up with the prodigious fundraising of Mr Obama, who has outspent Mrs Clinton by a margin of at least two to one in recent contests.

Mr Obama could afford to take a day off after what he called a decisive victory on Tuesday night. His chief strategist, David Axelrod, indicated that he would begin campaigning as the presumptive nominee and turn attention to the looming battle in November against the Republican nominee, Mr McCain.

Mrs Clinton raced from Washington to West Virginia, which holds a primary next week, and back again for an evening fundraising event. She also planned to cram in meetings with her top advisers and talks on Capitol Hill with wavering super-delegates who may now be preparing to file into her rival’s camp.

Mr Obama gained four new super-delegates last night, one of whom had switched her support from Mrs Clinton. Many super-delegates appear willing to wait until the final primaries on June 3, giving Mrs Clinton what one Democrat called “time to get out of the race on her own terms”.

Both sides acknowledge that the focus is now likely to shift from the remaining primary states, where only 217 delegates are at stake, to Washington, where battles over a larger number of uncommitted super-delegates as well as a dispute about 366 disbarred delegates from Florida and Michigan are likely to be fought.

Mrs Clinton wants the party’s punishment imposed on Florida and Michigan for staging their primaries in January lifted so that her victories there can be counted. Mr Obama’s team believes that this is an effort to “steal the nomination”, pointing out that his name was not even on the ballot in Michigan and that neither candidate campaigned in Florida.

Terry McAuliffe, Mrs Clinton’s national chairman, hinted at a possible compromise, saying that Mrs Clinton might accept a verdict giving the delegates half a vote each, which would cut Mr Obama’s lead by about 30, but perhaps allow her to catch him in terms of the popular vote.

If the party had “done what the rules say” by cutting just half the delegates, “we would not have any argument”, he told The Times.

Mrs Clinton is expected to hammer home claims that Mr Obama would be a weak candidate in November. Geoff Garin, her chief strategist, pointed out that Mr Obama trailed her by 24 per cent among white voters.But when she spoke in Indianapolis on Tuesday night, Tom Williams was offering discounts on his surplus stock of Clinton T-shirts. “This costs $10 but you can have it for 5. Right now it’s a devalued piece of merchandise.”

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