Hillary Clinton fuelled doubts yesterday about whether her White House campaign can survive further defeats at the hands of Barack Obama when crunch elections are held in Ohio and Texas next month.

“I don’t make predictions,” she said. “I just get up every day and do the best to let people know what I have done, what I am doing and what I will do.”

Her comments came hours after an emotional closing statement during a Democratic presidential debate in Austin, Texas, on Thursday night.

Asked about how she coped with crisis, Mrs Clinton responded by alluding to the sexual scandals of Bill Clinton’s White House. “I think everybody here knows I’ve lived through some crises and some challenging moments in my life.”

Then, reaching for her rival’s hand, Mrs Clinton shook her head and said: “No matter what happens in this contest I am honoured. I am honoured to be here with Barack Obama. Whatever happens, we’re going to be fine. I just hope that we’ll be able to say the same thing about the American people, and that’s what this election should be about.”

Her display of grace and unity touched a chord with the audience, which rose to its feet in applause. She has lost 11 consecutive contests to Mr Obama and with Mr Clinton saying that his wife must win Ohio and Texas on March 4 to stay in the race, her remarks were immediately interpreted as verging on the valedictory.

In television appearances yesterday she said that they were simply intended as a recognition of the “historic change” offered by the duel to be the first woman or black president.

Polls yesterday suggested that Mrs Clinton’s lead in Ohio had tightened but all but evaporated in Texas. Thursday’s debate had been viewed as one of her last chances to break Mr Obama’s gathering momentum. But she often appeared shy of throwing punches, twice refusing to say if her opponent — whose national security credentials have regularly been attacked by her campaign — was ready to be US commander-in-chief. Democratic party leaders have expressed concern that such a charge would be hard to claw back if Mr Obama becomes the presidential nominee in November’s election.

Although there was some gentle sparring over differences on Cuba, health policy and the economy, Mrs Clinton emphasised instead that she and Mr Obama were in agreement on most issues. The most significant clash was over recent allegations that Mr Obama had plagiarised speeches from his close friend and supporter, Deval Patrick, the Massachusetts Governor.

Mrs Clinton said: “Lifting whole passages from someone else’s speeches is not change you can believe in, it’s change you can Xerox.” Mr Obama shook his head and said such claims were just “silly”.

But, in a sign of the ill-feeling between the two campaigns, his aides pointed out later that Mrs Clinton’s closing remarks resembled those of her husband in 1992 and John Edwards, who dropped out of the race earlier this month. “Clinton’s ‘best moment’ someone else’s line?” asked Mr Obama’s spokesman, Bill Burton, in an e-mail.

Ann Lewis, a friend and aide to Mrs Clinton, described her remarks at the debate as “the Hillary I know — speaking from her heart”. Mark Penn, her chief strategist, said: “It was a real moment of connection with the audience. . . that I’ve not seen before.”

On a visit to Fort Worth yesterday, there was more emotion when Mrs Clinton said she was “heart sick” and cut short a rally after a police motorcycle outrider died in a traffic accident as he escorted her into the city.

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