Malcolm Rifkind: We Tories got it wrong over Iraq. Now we must rectify that

The Prime Minister has allowed himself and his country to be taken for granted by the Americans

But highly critical though I am, I recognise that the then Shadow Cabinet, under Iain Duncan Smith, supported Tony Blair because they were convinced that Iraq was a serious threat that justified military intervention to oust Saddam Hussein from power. Their agreement with the Government may have been unwise but it was not opportunistic. Far from it. They resisted the opportunity to defeat the Government because of their assessment of the national interest.

What I, and many other Conservatives, found far more difficult to understand was why the Shadow Cabinet continued to support the war even after the Prime Minister's justifications were completely discredited, in ways which are by now very familiar. At that time the Conservative Party would have been entitled to say that, like the British public and Parliament, they had been misled by the Prime Minister and that, as a consequence, their support was forfeit. That would have been an honourable and principled position. I regret that it was not adopted.

I do not think Iraq will have a material impact on the outcome of the Conservative leadership contest. While Ken Clarke and I can claim that our judgement has been vindicated by events and that public opinion has moved in our direction, it is far too late for the party to reap any political dividend by a reversal of the policy it has supported over the last few years.

Today, most of us who opposed the war accept that that does not give us the luxury of calling for the immediate withdrawal of troops. Britain cannot shirk its responsibility to do all within its power to help the new Iraqi government defeat the insurgents and the terrorists and try to bring some semblance of security and democracy to that country.

Nor would it be sensible to impose any deadline on the presence of British troops. To do so would merely encourage the insurgents and their jihadist allies to continue their terrorist campaign in the sure knowledge that the coalition would pull out at a defined date and Iraq would then succumb to their tender mercies.

The Conservative Party does, however, have important obligations as the major opposition party in Parliament. It needs to hold the Government to account for its current as well as its past Iraq policy. Two vital issues should be addressed.

Firstly, there is scant evidence that Tony Blair has any influence on US policy in Iraq. As the United States' main ally, the Prime Minister and the Foreign Secretary should be part of the innermost councils of its planning and thinking. As Sir Christopher Meyer, our ambassador in Washington at the start of the war, embarrassingly revealed, Blair has made little effort to assert his influence. That is deplorable.

Secondly, many of the coalition's smaller partners have either already withdrawn their troops from Iraq or will do so over the next few months. Britain is becoming ever more exposed. Until there is a proper internationalisation of the peace-keeping forces it will still seem to many Iraqis that they are an occupied country. This will continue to be a major recruiting agent for the insurgency. Blair needs to tell the President that America must persuade other countries, especially moderate Arab states, to contribute towards peace-keeping and that that will involve sharing power and decision-making with them.

There is one other respect in which Iraq should have a serious impact on Conservative thinking and that is on Britain's relationship with the United States. All British prime ministers, Labour as well as Tory, have valued a close relationship with Washington. Tony Blair is, however, the first to be regularly lampooned as America's poodle. So embarrassed is he that he has not, even, felt able to go to the United States to receive the Congressional Medal of Honor.

The reason is very simple. Blair's support for Bush has been, and has been seen to be, unconditional. Harold Wilson refused LBJ's request for troops in Vietnam; Thatcher handbagged Reagan over Grenada; Major clashed with Clinton on Bosnia. No lasting damage was done to US-British relations. Indeed, at the height of the Bosnian disagreement the Americans tried to persuade Douglas Hurd, the architect of Britain's policy on Yugoslavia, to be the secretary general of Nato. The Americans are mature grown-ups. They know that even close allies can, sometimes, disagree. Blair, however, from a mixture of naivety and incompetence, has allowed himself and his country to be taken for granted.

It has been unedifying and it has damaged Britain's reputation and interests. The Conservative Party should hold him to account. It is not just a political opportunity; it is a national duty.

Sir Malcolm Rifkind MP is a former foreign secretary and a candidate for the Conservative Party leadership