Barack Obama hurled himself into an angry confrontation with the President yesterday after Mr Bush compared the Democratic candidate’s promise of talks with rogue states like Iran to the “false comfort of appeasement” towards the Nazis in the 1930s.

“Some seem to believe that we should negotiate with the terrorists and radicals, as if some ingenious argument will persuade them they have been wrong all along,” Mr Bush told the Knesset in Israel. “We have heard this foolish delusion before. As Nazi tanks crossed into Poland in 1939, an American senator declared: ‘Lord, if I could only have talked to Hitler, all this might have been avoided’.”

Even though the White House insisted that Mr Bush was not talking specifically about Mr Obama, the Democrat Senator issued a statement denouncing what he called a “false political attack”. He said: “The President’s extraordinary politicisation of foreign policy and the politics of fear do nothing to secure the American people or our stalwart ally, Israel.”

The speed and force of his reaction reflects how he is increasingly focused on a looming general election against the Republicans, having all but won his fight with Hillary Clinton for the Democratic nomination. But it was also a sign of some sensitivity in Mr Obama’s campaign to charges that he is inexperienced and naive on foreign policy, particularly among the influential Jewish and pro-Israel lobby.

He has pledged to meet the leaders of states such as Iran, Cuba and North Korea during his first year in office – insisting that this would not include “terrorist organisations”. Last week one of Mr Obama’s advisers quit his team abruptly after admitting that he had already contacted the militant Islamist group Hamas.

On Wednesday night Mr Obama had taken a big step to addressing another flaw in his electoral appeal by securing the endorsement of John Edwards, a former presidential rival who maintains strong support among the white working-class vote, which has largely rejected Mr Obama in recent Democratic primaries, including West Virginia this week.

At a raucous rally in a stadium in Grand Rapids, Mr Edwards declared: “The Democratic voters have made their choice, and so have I.” There was “one man who knows in his heart that it’s time to create one America, not two – and that man is Barack Obama,” he added.

Although Michigan is more fertile general election territory for Mr Obama than the rural hills of West Virginia, he knows he needs help reaching out to voters who share many of the same economic concerns.

Mr Obama sought to build bridges with blue-collar workers who regard him as an elitist, even unpatriotic, figure. He toured a Chrysler assembly line wearing, in his lapel, the American flag pin he once eschewed.

He spoke later about the need for lower petrol prices, the need for “bot-tom-up economic growth” and insisted that a speech last year interpreted widely as an attack on Detroit’s car-makers had “gotten a bad rap”.

Mr Obama acknowledged that Mr Edwards’s backing – which effectively obliterated Mrs Clinton’s tour of evening news programmes after her West Virginia win – “will help some of those supporters who haven’t already joined my campaign to take a look at my campaign”. Neila Casarez, a 30-year-old health worker, said: “I love John Edwards. He would have been my choice for president even ahead of Obama – and now I want him to be vice-president.”

There is already speculation that Mr Edwards, who was the Democratic vice-presidential nominee in 2004, could join the ticket once more in November. Although some of the biggest names, including the former Vice-President, Al Gore, the House Speaker, Nancy Pelosi, and the Senate leader, Harry Reid, remain officially neutral, another sign that the party is now uniting behind Mr Obama could be seen in the way Howard Dean, the Democratic chairman, sprung to the defence of the presumptive nominee as he denounced Mr Bush’s remarks.

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