The Prime Minister asserted that the visit had come at “exactly the right time” and that it would be a disaster for both sides if Europe allowed anti-Americanism to define its foreign policy.

But according to a Populus survey for The Times, half the public believe that the strong personal relationship between Mr Blair and Mr Bush is bad for the country. Voters, particularly women, strongly disapprove of his handling of the Iraq war and do not believe he is up to being president.

As the Prime Minister faced the controversy over the three-day visit head on, the survey provided further embarrassment for both leaders. The trip is widely expected to be marred by anti-war demonstrations and there are frantic efforts by security officials to prevent it being disrupted.

According to the survey, only one in four voters approves of the President’s handling of the war and overall support for the war in Britain has fallen heavily.

Nearly three fifths of voters (59 per cent) think America’s standing in the world has diminished under the Bush presidency, while less than two fifths (39 per cent) think he has proved a strong president.

Mr Blair used his annual speech to the Lord Mayor’s Banquet last night to pre-empt the protests that he accepts are certain and to declare that the argument should no longer be about the war but about the battle to reconstruct Iraq.

Now was the time to win the peace and that could only be done if Europe worked closely with the United States and the United States with Europe, he said. The West must not retreat one inch until Iraq was free of the terrorist menace.

“For many, the script of the visit has already been written,” he said. “There will be demonstrations. His friends wonder at the timing. His enemies rub their hands at what they see as potential embarrassment.

“I believe this is exactly the right time for him to come. Let us be clear what is happening in Iraq. Leave aside the rights and wrongs of the conflict, upon which I admit there can be legitimate disagreement.

“What is happening now is very simple. It is the battle of seminal importance for the early 21st century and it will define relations between the Muslim world and the West. It will have far-reaching implications for the future conduct of American and Western democracy.”

The people trying to bomb the United Nations and Iraq out of Baghdad, and killing Iraqi civilians in terrorist attacks, were Saddam Hussein’s small rump of supporters aided by foreign terrorists. They were doing it because they knew that if Iraq were set on the path to prosperity and democracy “it means the death of the poisonous propaganda monster about America that these extremists have created in the minds of much of the world. What these fanatics are doing now in Iraq is not irrational. It is an entirely rational strategy.

“I say to those who will protest when President Bush comes: protest if you will, that is your democratic right. Attack the decision to go to war, though have the integrity to realise that, without it, those Iraqis now tasting freedom would still be under the lash of Saddam.”

In a sideswipe at Donald Rumsfeld, the US Defence Secretary, he said they should dismiss the illusion that there was an old and a new Europe, one opposed to the US and on its way out and the other the bright harbinger of the future. Mr Rumsfeld labelled France and Germany “old Europe” when they opposed the war.

Mr Blair answered American concern over proposals for European defence co-operation by saying that British participation on the right terms would ensure that European defence developed in a way consistent with Nato. If Britain did not take part it would still happen, but without her. “That is not sensible for Britain, for Europe or for America.”

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