Now Bush blames failure to find WMD on looters

It has taken more than two months. But belatedly, from his Democratic challengers for the White House and in committee rooms on Capitol Hill, President George W Bush is starting to feel the heat of the controversy over Iraq's missing weapons stockpiles.

In his weekly radio address yesterday, Mr Bush was forced to produce a new explanation of why the US has not found Iraq's alleged chemical and biological weapons. He told listeners that suspect sites had been looted in the closing days of Saddam Hussein's regime.

But this rationale is no more likely to still the gathering debate than the President's dismissal last week of the "revisionist historians" who doubt the administration's pre-war claims that Iraq not only possessed a huge chemical and biological weapons arsenal and an active nuclear weapons programme, but had close links with the al-Qa'ida terrorist organisation.

Mr Bush hitherto has faced nothing like the pressure on his ally Tony Blair in Britain - partly because the war always enjoyed greater public support here, making his Democratic opponents wary of challenging a popular president on national security.

More fundamentally, most Americans still do not accept the critics' premise. One recent poll found that a third of the population actually believes that weapons have been discovered, even though the best investigators have come up with are a couple of vehicles some experts say might have been mobile bio-weapons laboratories. According to a Gallup survey last week, 83 per cent of Americans believe Saddam was developing nuclear arms, despite no serious evidence to support that view.

The tide, however, may at last be starting to turn. On Capitol Hill, powerful committees are cranking up for hearings into the performance of the intelligence agencies before the war, and whether their findings were exaggerated by the administration.

On the campaign trail too, Democratic candidates are finding a voice. Bob Graham of Florida, former chairman of the Senate Intelligence Committee, has declared that Mr Bush "politicised and manipulated" the evidence. Even more telling could be the broadside delivered by Senator John Kerry of Massachu-setts, an early front-runner for the presidential nomination.

Mr Kerry, a Vietnam war veteran and an expert on national security, had previously been circumspect on the issue - not least because of his support last autumn for the Congressional resolution giving Mr Bush virtual carte blanche to use force against Saddam. But in fiery remarks in New Hampshire, where the critical primary takes place in January, he accused Mr Bush of lying. "He misled every one of us," he declared, vowing that Congress would get to the bottom of the matter.

But it is anything but certain he can deliver on that. Republican control of both chambers means Mr Bush's party has the majority on the committees gearing up to investigate. In any public hearings, for which Democrats are pressing, key administration witnesses may avoid questioning by citing national security concerns.

The Democrats themselves are also divided. The former House minority leader Richard Gephardt and Senator Joe Lieberman, Al Gore's running mate in 2000, remain among the strongest supporters of the war.

All these factors explain why Mr Bush has enjoyed what an envious Mr Blair must consider a free ride so far. That state of affairs is only likely to change if the security situation inside Iraq deteriorates to a level where resistance can no longer be attributed to "dangerous pockets of the old regime" and their "terrorist allies". At that point public opinion will start to ask in earnest why the war was launched in the first place.