Barack Obama, the Democratic presidential contender, pleaded with voters in Iowa yesterday to cast aside doubts about his lack of experience, amid signs that Hillary Clinton had stabilised her troubled campaign and regained the initiative.

Standing before an overflowing crowd in Des Moines, a week before crucial January 3 caucuses in Iowa kick off the presidential nominating process, Mr Obama gave the most powerful speech of his campaign, urging the crowd to reject the Clintons’ politics of cynicism and fear in what his campaign calls his “closing argument”. It came as a new poll claimed to show that, after months of deadlock in Iowa, Mrs Clinton had suddenly opened a wide lead. The new American Research Group poll put Mrs Clinton 15 points ahead of Mr Obama, only a week after it had the two in a statistical tie. According to the survey, Mr Obama had suffered a dramatic 11-point drop in support among men.

Iowa polls are notoriously unreliable, and most analysts believe that the race in the Hawkeye State is still a close three-way contest between Mrs Clinton, Mr Obama and John Edwards. But the survey increased anxiety in the Obama camp that Mrs Clinton’s relentless message of experience, versus Mr Obama’s theme of change, may be having more resonance in the final, frantic stretch of campaigning.

To amplify those concerns, the assassination of Benazir Bhutto, the former Prime Minister of Pakistan, came a day after Mrs Clinton, for the first time, played on voters’ fears by declaring the world dangerous and unpredictable, as she crisscrossed Iowa with her husband, Bill, and daughter, Chelsea, on her new “It’s Time to Pick a President” tour. Without mentioning Mr Obama by name, Mrs Clinton asked crowds if they were ready to put their faith in an untested leader when “you never know what may happen in some part of the world that will create a real challenge to us here at home”.

Late last night the Clinton campaign reacted furiously to a suggestion by Mr Obama’s campaign manager that Mrs Bhutto’s assassination was linked to Mrs Clinton’s vote authorising the Iraq war.

David Axelrod said Ms Bhutto’s death will “call into issue who has made the right judgment”. He said the resurgence of al-Qaeda in Pakistan was “a consequence of us taking the eye off the ball and making the wrong judgment in going into Iraq”.

Phil Singer, a Clinton spokesman, said: “No one should be politicising this situation with baseless allegations.”

Mr Obama, who was introduced by General Tony McPeak, a decorated Vietnam fighter pilot and former Air Force chief of staff, responded with the most forceful and aggressive address of his White House attempt. “We can’t afford the same politics of fear that invokes 9/11 as a way to scare up votes,” he declared before banners proclaiming a new slogan: “Stand for Change.” In a clear reference to comments by Mr Clinton last week that an Obama presidency would be a “roll of the dice”, Mr Obama said: “The real gamble in this election is playing the same Washington game with the same Washington players and expecting a different result. And that’s a risk we can’t take. Not this year. Not when the stakes are this high.”

Mr Obama did not refer to the Clintons by name, but he did not have to. He spoke of the cynics who had been scornful of his message of hope when he launched his candidacy ten months ago. He talked of the “attack ads and insults, the distractions and dishonesty” aimed against him as his campaign took off in the autumn. “Ten months later, Iowa, you have vindicated that faith.

“If you’re ready to stop settling for what the cynics tell you you must accept, and finally reach for what you know is possible, then we will win this caucus, we will win this election, we will change the course of history.” The largely partisan crowd gave him a standing ovation.

As Mr Obama and the Clintons campaign relentlessly for the next week, their greatest challenge is not just the bitter Iowa cold, or the prospect of enthusing caucus-goers on New Year’s Day. It is Mr Edwards who has a significant chance of winning the state. All the campaigns concede that the Democratic race is still extremely volatile.

Battle for Iowa

34% Democrats in Iowa said that they would vote for Hillary Clinton

19% said that they would back Obama

38% of women said that they supported Clinton, 23% Obama

28% of men would vote for Clinton, 27% John Edwards, 16% Obama

23% of Republicans said that they would support Mike Huckabee

14% would vote for Rudy Guiliani

20% of men would vote for Huckabee and Guiliani

26% of women would vote for Huckabee and Mitt Romney

Source: latest Iowa poll by American Research Group

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