John McCain faced further questions about his age yesterday after John Kerry, the Democrats’ 2004 presidential nominee, described the 71-year-old Republican as “confused” over Iraq.

“I’m obviously disappointed in a comment like that,” Mr McCain said after a clash between his presidential campaign and that of Barack Obama over remarks that the Republican made about US troop levels in Iraq.

Mr McCain - who, if elected, would be the oldest first-term president - has confronted the issue of his advanced years head on, joking about it frequently at campaign events and on television.

At the same time, he and his surrogates have reacted fiercely to any suggestion or perceived innuendo from the Obama campaign that his mental faculties are impaired.

The flare-up came as the first poll numbers since Mr Obama clinched the Democratic nomination emerged. In a Wall Street Journal/NBC survey, he leads Mr McCain nationally 47 to 41 per cent. It suggests a competitive race and demonstrates that so far Mr McCain has managed largely to inoculate himself from the unpopularity of the Republican brand.

On Wednesday he was asked by an interviewer whether he had a more accurate estimate of when US troops could return from Iraq if the “surge” he advocated was now working.

“No, but that’s not too important,” he replied. He went on to say that the most important goal was reducing troop casualties in Iraq, and that US forces were still in South Korea, Japan and Germany without suffering harm.

The Obama campaign pounced on the remarks, accusing Mr McCain of being insensitive to the sacrifices of US troops. In a conference call with reporters Mr Kerry repeatedly called the Arizona senator “confused” on Iraq, noting that on two occasions he had mixed up Sunnis and Shias and had also wrongly stated which armed groups Iran was backing.

Mr Kerry strongly denied that he was alluding to Mr McCain’s age when he called him confused.

As first reported in The Times last week, Mr Obama’s campaign unveiled a “web-based rumour clearing-house” to rebut online smears over his religion, his family and personal ties. It will use fightthesmears.com, and ask millions of online supporters to participate, to get false claims about him and his family - particularly a persistently false claim that he is a Muslim - tracked down in cyberspace and sent there.

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