In the long-awaited encounter between the two men, Mr McCain attacked Mr Obama's foreign policies as “na?ve and dangerous” while Mr Obama accused his Republican rival of continuing the economic policies of George W. Bush and sought to connect with the problems of ordinary voters.

But, despite the barbs traded in the debate, the two men set out a series of policies that were sometimes close to each other in substance, with notable exceptions, among which tax and spending policy was particularly prominent. Indeed, on the topics of Iran and energy policy, the two men appeared to shift positions closer towards each other.

In a CBS News poll of uncommitted voters who watched the debate, 39 per cent thought Mr Obama won while 24 per cent considered Mr McCain the victor. In a Fox News focus group most viewers said Mr Obama had emerged the winner.