Colonel Lawrence Wilkerson, former chief of staff to Secretary of State Colin Powell, could hardly be counted a friend of the White House. In a blistering address at a Washington think-tank last month he charged that a small “cabal” led by Vice-President Dick Cheney had hijacked US foreign policymaking and led the US to a disastrous war in Iraq.

But Col Wilkerson gave an unlikely defence of the administration in one area – its handling of the intelligence on Iraq’s alleged efforts to develop weapons of mass destruction. While Democrats in recent days have escalated charges that the administration manipulated intelligence to win public support for the war, Col Wilkerson said “the consensus of the intelligence community was overwhelming”.

He said that Mr Powell’s February 5 2003 address to the United Nations – which laid out the US intelligence case against Saddam Hussein – relied on conclusions that were widely shared. “I can’t tell you why the French, the Germans, the Brits and [the US] thought that most of the material, if not all of it, that we presented at the UN . . . was the truth. I can’t. I’ve wrestled with it.”

Those conclusions underscore the difficulty Democratic critics face in persuading the American public that the war was launched on a lie. Since re-opening the issue earlier this month, the Democrats have grown increasingly aggressive in insisting that the administration went far beyond even the flawed intelligence in making its public case for the war.

John Kerry, the Democratic presidential candidate in 2004, on Monday accused President George W. Bush of orchestrating “one of the great acts of misleading and deception in American history”. He charged that “weapons of mass destruction were just the first public relations means to the end of removing Saddam Hussein”.

John Edwards, his running mate and a former US senator, wrote in the Washington Post at the weekend that he should never have voted to authorise the war. “The intelligence was deeply flawed and, in some cases, manipulated to fit a political agenda,” he wrote.

Mr Bush and his senior advisers have been fighting back. In a speech in Alaska on Monday night, en route to Asia, the president said: “Reasonable people can disagree about the conduct of the war – but it is irresponsible for Democrats to now claim we misled them and the American people.”

Both the administration and Democrats “looked at the same intelligence on Iraq, and reached the conclusion that Saddam Hussein was a threat”, he said.

The Republican National Committee on Tuesday put out a video called “Democrats: Dishonest on Iraq”, which highlights prewar statements by top party officials on the threat posed by Iraq.

While two investigations have absolved the administration of deliberately “politicising” the work of the intelligence agencies and pressing analysts to change their conclusions on Iraq, neither directly addressed the question of whether the White House distorted the available intelligence in making its case for war. The Senate intelligence committee has just begun examining that question seriously.

The most detailed investigationto date – by the Carnegie Endowment for International Peace, a Washington think-tank – concluded last year that there were serious distortions in the administration’s public presentation of the intelligence findings. Among the worst, it said, were:

■ The repeated use of the phrase “weapons of mass destruction”, which “lumped together the high likelihood that Iraq possessed chemical weapons, which themselves constitute only a minor threat, with the complete lack of evidence that it possessed nuclear weapons, which would be a huge threat”.

■ The repeated insistence that Iraq might give WMD to terrorists, even though US intelligence said that was highly improbable.

■ The exaggeration of intelligence findings. In one instance, UN inspectors had reported that Iraq had failed to account for biological material that “could have” produced large quantities of anthrax. In an October 7 2002 speech in the build-up to war, Mr Bush claimed that UN inspectors had “concluded that Iraq had probably produced . . . a massive stockpile of biological weapons that has never been accounted for and is capable of killing millions”.

The report said that “small changes like these can easily transform a threat from minor to dire”.

The administration’s attempt to justify those past distortions has already thrown up several new ones. In an effort to prove that Democrats were equally at fault, the White House this week put out selective quotes from Mr Kerry and from Senator Carl Levin, a Michigan Democrat, implying that as far back as December 2001 they had both supported ousting Saddam Hussein as part of the “war on terror”.

But the full quotations make it clear that neither thought a war was justified unless it could be shown clearly that Mr Hussein was linked to the September 11 attacks.

So far, the Democrats appear to be getting the upper hand in what has become a war of words over how the US got into Iraq.

A Newsweek poll released on Monday found that 52 per cent of Americans thought the administration misused or manipulated the prewar intelligence, while 33 per cent thought it had not. Only 30 per cent supported Mr Bush’s handling of the war in Iraq, and 45 per cent on terrorism and homeland security. His overall job rating – 36 per cent – was the lowest yet recorded.

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