Duncan Smith is doomed - but don't count on Howard to succeed him

The nightmare scenario would be for IDS to win the confidence ballot by a few votes. Anarchy would rule throughout the party

Iain Duncan Smith is determined but he is also extremely stubborn: he has now chosen to wreak havoc and mayhem on the Conservative Party by prolonging his fight. His statement yesterday had echoes of Margaret Thatcher's "I fight on, I fight to win". He is doomed and he must surely know that he cannot press on. The Conservative Mental Health Summit takes place in Parliament at 9.30am today but, sadly, it is unlikely to be that well attended. Perhaps Mr Duncan Smith and Tory MPs might do well to take a break, however, from their party's bout of madness to consider their own mental state before going on to that other meeting, at 2.30pm, of the 1922 Committee, to watch Mr Duncan Smith make his last futile stand. MPs will then vote, immediately, on the motion of confidence.

October and November are, historically, a time for plots and treachery in Parliament. Guy Fawkes chose 5 November, 1605, the day of the State Opening, for his gunpowder plot. Geoffrey Howe and Michael Heseltine chose the same time of the year, in 1990, to bring down Margaret Thatcher. And, in this very week last year, the Tories were in a state of convulsion over Mr Duncan Smith's policy of opposing gay adoption. That led to the resignation from the shadow cabinet of John Bercow followed by the infamous "unite or die" press conference - on 5 November.

Regardless of Mr Duncan Smith's determination to face down his critics in the formal ballot on the motion of confidence in his leadership, there will undoubtedly be a new leader of the Conservative Party. The autumnal fog that has enveloped the corridors of Westminster this week, with MPs unwilling to be seen speaking to journalists, has lifted to reveal a party in utter disarray. It is even conceivable that it could all be over for Mr Duncan Smith by tonight - before a single vote has been cast.

The audacious move that might have guaranteed his survival has turned out to be yet another disaster now that his bluff has now been called. While there may have been something rather impressive, brave and noble about his press conference where he challenged his MPs to support him, he was wasting his breath. In the ballot which follows immediately after he attends the meeting of the 1922 Committee, in Room 14 this afternoon, his death warrant will certainly be signed.

Now there are 25 letters, in the hands of Sir Michael Spicer, the 1922 Committee chairman, Mr Duncan Smith has absolutely no chance of winning such a ballot. The decision of Francis Maude, the former cheerleader for Michael Portillo, to join Derek Conway, Crispin Blunt and John Greenway clearly emboldened those more anonymous and cowardly colleagues who also want to remove Mr Duncan Smith. Many of these were afraid of being accused of treachery and then suffering the consequences of de-selection in their constituencies. But equally, they would have been regarded with derision by both pro- and anti-leadership forces if they had expected others to do their dirty work.

Sir Michael has been utterly inscrutable - although his reply to Mr Conway thanking him for his letter, "the terms of which I fully understand and accept", indicated that he must have been preparing to serve a new leader. Indeed, one wonders if he even wrote a letter to himself.

When Mr Duncan Smith walks through the phalanx of hacks down the long committee corridor to Room 14 to meet his makers, he could be carrying two speeches. At this stage it is difficult to know which one he will make. The first would echo his statement yesterday that he will not resign but will face the secret ballot of all 165 Tory MPs on the proposition whether or not they have confidence in his leadership. A simple majority of 83 votes, or more, against Mr Duncan Smith seals his fate. Party insiders are predicting that there will be an avalanche against him and he will be lucky to score even 20 votes. This would be an utter and undeserved humiliation. But do not under-estimate the determination of the quiet man not to go quietly.

The nightmare scenario would be for Mr Duncan Smith to win the confidence ballot by a few votes. Technically he would have the right to carry on but his authority would be in tatters. Anarchy would rule throughout the party, since the control mechanism through which authority is delivered, the whips' office, is now inoperable. At least two whips are known to be actively working against Mr Duncan Smith and were encouraging MPs to send in letters to Sir Michael. The chief whip, David MacLean, is a man of great experience but many of his pronouncements, which he has deliberately made public, seem bizarre - unless, of course, he is already preparing for life after Mr Duncan Smith.

Mr Maclean's office, and the way it is currently being run, reminds me of a similar situation before the fall of Margaret Thatcher. The then chief whip, Tim Renton, was suspected of contributing to the vulnerability of her position. He was viewed by many, myself included, as a close supporter of Geoffrey Howe and therefore complicit in creating some of the circumstances that led to her downfall.

The other speech, the one that Mr Duncan Smith should deliver, would signal his withdrawal in the face of overwhelming odds. For all his bravado, which is entirely understandable and necessary while he remains in play, he ought to make a graceful retreat leaving his enemies reaching for their handkerchiefs to wipe away their crocodile tears - again with reminders of the 1990 Thatcher downfall.

Whatever happens tonight, however, will not end the Tories' nightmare, which is just beginning. With echoes of 1990 to guide me, I see the scene shifting behind the closed doors of the shadow cabinet room. So far, members of the shadow cabinet have largely kept their powder dry. But this will not endure. Resignations will follow tonight's events, regardless of the outcome. After Mrs Thatcher had been wounded - but not killed - following the indecisive first ballot, she pledged to carry on. But the refusal of her cabinet colleagues to serve, even if she were to be successful in further ballots, meant that votes and margins of victory became irrelevant.

Who will be the successor? On the basis of previous contests I would advise readers of a betting persuasion to discount the favourite, currently Michael Howard, and go for the most obscure. If there is a Tory MP of whom no one has ever heard I should recommend putting a fiver on such an outsider. This time, however, I have a feeling that the soap opera the Tory party has become has run its course. The media are getting tired of being used as unwitting conduits. MPs of all views and persuasions - and even rival successors - may just be in the mood for grown-up politics and a real and competent opposition. So here's probably to you Mr Howard - providing you get in touch with David Davis and speak nicely to him. But dream ticket scenarios may still be some way off - with Mr Ancram, Tim Yeo and perhaps even Ken Clarke gearing up for action.

mrbrown@pimlico.freeserve.co.uk