The British and US governments are drawing up a controversial new strategy to convince the public that Saddam was developing weapons of mass destruction - an admission that they have so far failed to make a convincing case.
The "big impact" plan is designed to overwhelm and silence critics who have sought to put pressure on Tony Blair and George Bush. At the same time both men are working to lower the burden of proof - from finding weapons to finding evidence that there were programmes to develop them, even if they lay dormant since the 1980s.
In press conferences on either side of the Atlantic on Wednesday, the Prime Minister and the President both conceded that to maintain trust, they would have to prove their pre-war claims on WMD. "In order to placate the critics and cynics about intentions of the United States, we need to produce evidence," Mr Bush said. "And I fully understand that. And I'm confident that our search will yield that which I strongly believe: that Saddam had a weapons programme."
Mr Blair said that "people need to know that what we did in Iraq was right and justified. That's a case we have to not just assert, but prove over time, both in relation to weapons of mass destruction and in relation to the improvement of Iraq. I think a lot of people will make up their minds on the basis of the evidence."
But the Prime Minister gave a clear signal of the strategy by adding: "There has always been something bizarre about the notion that Saddam never had any weapons of mass destruction." His critics say that is beside the point: the question is whether the US and Britain can prove their claims that he still had them in sufficient quantities to pose an imminent threat to the world.
Officials say that WMD information is being collected and collated to create a "big impact". Both Downing Street and the White House are said to have learnt tough lessons from the experience of February's "dodgy dossier" on Iraq and the false claims about Iraqi efforts to buy uranium from Africa.
"Instead of just putting out pieces of a jigsaw and expecting people to see the picture, they are waiting until they have more pieces," said one official involved in the project. "They want to get it right." The authorities had learnt not to put out piecemeal information without proper verification, he added.
A presentation could be made as soon as September, with the aim of providing a boost to Mr Blair ahead of the Labour Party conference at the end of the month, and to Mr Bush as the presidential campaign gathers steam. Officials speak confidently of the hard evidence they claim has been gathered in Iraq since Saddam was ousted three months ago.
The Bush administration has brought in a former UN weapons inspector, David Kay, as civilian chief of the Iraq Survey Group, the military- intelligence unit that is heading the hunt for WMD. Last week, having given evidence to closed-door sessions of the US Senate's armed services and intelligence committees, Mr Kay outlined the strategy. "We do not intend to expose this evidence until we have full confidence that it is solid proof," he said. "The American people should not be surprised by surprises. We are determined to take this apart and every day we're surprised by new advances that we're making."
It is not clear how the evidence would be unveiled, though some have suggested it could be similar in scope to the presentation the Secretary of State, Colin Powell, made to the UN Security Council last February. Parts of that seemingly convincing exercise were later found to have relied on highly questionable evidence, however, and one official predicted the new presentation would be a "sober assessment".
Mr Kay told the committees that progress of the survey group had been slow, despite claims by the administration before the war that it had intelligence that would lead them to weapons sites. Interrogations of the regime's top scientists have not led to dramatic discoveries, although he claimed they were giving valuable information.
"It's going to take time," Mr Kay said after one hearing. "The Iraqis had over two decades to develop these weapons. And hiding them was an essential part of their programme. We're not close to a conclusion yet."
John Rockefeller, the senior Democrat on the intelligence committee, said: "I remain cautious about whether we're going to find actual WMD. Not just a programme, but the very extensive weapons - ready for attack - that we all were told existed."
Scott Ritter, the former chief UN weapons inspector and an outspoken critic of the Bush administration's WMD claims, said Mr Kay had nothing of substance to tell the committees. "His job is not to tell the truth - it's to provide political cover for the President. He was brought back from Iraq not because he has anything relevant to say, but because the President needs to buy time. There is nothing of substance in anything he has said."