Tony Blair turned down a last-minute offer from President George Bush for Britain to stay out of the Iraq war because he thought it would look "pathetic", according to a new book on Mr Blair's tenure.
Mr Bush was warned by the US embassy in London before the crucial Commons vote on the war that the Blair government could be brought down. He was so worried that he picked up the telephone and personally offered the then Prime Minister a surprise opt-out.
Mr Bush's move is revealed in the book Blair Unbound, by Anthony Seldon, Peter Snowdon and Daniel Collings, to be published by Simon & Schuster next Monday. It is bound to heighten criticism of Mr Blair's stance on Iraq.
Nine days before the Commons backed military action, despite a rebellion by 139 Labour MPs, President Bush astonished Condoleezza Rice, who was his National Security Adviser, by suggesting that Britain need not join the invasion and could play a less controversial role during the aftermath.
According to the book, the US embassy in London was sending Washington worrying accounts of Mr Blair's position. "We were talking to backbenchers. What we heard was a fairly strident message that there was only so far that we could go, and the UN was extremely important. We heard some very ominous analyses of what could happen," said one official.
Ms Rice told the book's authors: "I remember standing in the Oval Office, and the President said, 'We can't have the British Government fall because of this decision over war.' I said: 'So what are you saying?' He said, 'I have to tell Tony that he doesn't have to do this.'"
Ms Rice's first thought was to call Sir David Manning, her opposite number in Downing Street, to prepare the ground but Mr Bush judged there was no time. "I'm going to call him right now," he said.
"What I want to say to you is that my last choice is to have your government go down," he told Mr Blair. "We don't want that to happen under any circumstances. I really mean that."
If it would help, he would let Mr Blair "drop out of the coalition" and the US would find some other way for Britain to participate. Ms Rice described the conversation as "very emotional" for the President.
Mr Blair replied: "I said I'm with you. I mean it." One confidant explained: "Having taken it so far, backing out seemed to him a rather pathetic thing to do."
The book also claims that Colin Powell, who was Secretary of State, plotted with Jack Straw, the Foreign Secretary, to persuade Mr Blair to restrain President Bush. But the former prime minister did not stand up to him when the crunch came.
Mr Powell told the authors: "In the end Blair would always support the President. I found this very surprising... Jack [Straw] and I would get him all pumped up about an issue. And he'd be ready to say 'look here, George.' But as soon as he saw the President he would lose his steam."
The book says Mr Blair decided in 2002 to write to the President to express concern that the momentum towards war was growing too fast. But he "faltered and pulled his punches" and in effect told President Bush: "You know, George, whatever you decide to do, I'll be with you."Reuse content