The last thing Mr Duncan Smith needed was a bold new crew-cut

It takes some doing. As Tony Blair enters his most precarious period since he came to power the Conservatives renew their civil war. Perhaps Iain Duncan Smith is a closet Labour supporter and wants to help out the Prime Minister in his hour of need. He has certainly done him a big favour.

Given that Mr Duncan Smith has revealed no leftward leanings in the past, I offer an alternative reason for his bizarre behaviour. The Conservative leader has become obsessed by opinion polls. The more he protests in public about how he does not bother too much about them, the more you can be assured he neurotically reads every damned statistic published by polling organisations around Britain. Recently one or two polls have shown a significant narrowing of the Labour lead. One survey put the Conservatives a single point behind Labour. Leaders who are used to reading dire findings leap on such statistics. They do more than that. They caress them, parade them, re-read them – and often draw the wrong conclusions.

The slightly improved poll findings coincided with a period in which Mr Duncan Smith tried to appear more robust on the asylum issue and the need for tax cuts. So that was it: he resolved to be tough, to be bold, to be himself. William Hague removed his baseball cap and acquired a crew-cut. Mr Duncan Smith sacked the "modernisers" in Central Office and replaced them with old right-wing friends. At the same time, he put John Redwood on full alert to make another of his comebacks. Under Mr Hague, Mr Redwood's comeback took the insulting form of a "campaigning role outside the Shadow Cabinet". If you recall the nonentities inside Mr Hague's Shadow Cabinets you will realise just how insulting this was to Mr Redwood. Mr Duncan Smith's Shadow Cabinet is no more charismatic, but it appears that before very long Mr Redwood will be very much on the "inside", another symbol of a shift to the right, of Mr Duncan Smith's own version of a "crew-cut phase".

IDS had a go at "compassionate conservatism", but he could not really pull it off. He is a Thatcherite Conservative, a nice chap with deeply entrenched right-wing views. He is not a Neil Kinnock, who was a left-winger determined to pull his party towards the centre. The current Conservative leader is a right-winger who has half-heartedly flirted with the centre ground and has had enough of it. As far as he is concerned he is leading his party back to where it belongs.

Which means its appeal at the next election will not be very different from the last. Unless of course, IDS is removed. In my view a leadership challenge is now inevitable. Significantly, his opponents are starting to stir more visibly and loudly. This never happened under Mr Hague. Most of the time internal opponents kept their heads down. Michael Portillo's decision to give a critical interview to The World at One on Friday followed conversations with several despairing Conservative MPs: "Speak out, Michael," they shrieked. So he spoke out in a way that he never did during the Hague era.

Mr Portillo is in the relatively safe position of not seeking the leadership. He is enjoying himself too much making programmes on Wagner and hosting televised dinner parties – largely unwatched – on BBC4. When he speaks publicly he does so because he believes in what he is saying rather than out of political ambition.

He speaks for a significant number of Conservative MPs, some of whom are not normally Portillo admirers. In the past few days several senior backbenchers have told me they are now convinced Mr Duncan Smith would lose badly in a ballot of the parliamentary party. There continues to be a single obstacle to bringing about such a ballot. Dissenting MPs risk the vengeful wrath of their constituency parties by organising a vote of no confidence in their leader, the essential pre-condition for a leadership contest. I spoke to one who speculated about hiring a large country house where a group of backbenchers could meet and do the deed, there being safety in numbers. I laughed at this suggestion until I realised the MP was being serious, or almost serious. IDS is in deep trouble. Tory MPs have moved on from regarding the trigger for the contest as an insuperable block. If you bump into a bunch of Conservative MPs in an obscure country hotel over the next few weeks you will know the brief leadership of Mr Duncan Smith is as good as dead.

The Tories are mirroring Labour in the 1980s in more ways than one. First they contrive a crisis when the Government is in trouble. Margaret Thatcher once displayed a hint of a sense of humour when she observed of Labour when the knives were out for her: "They keep on fighting each other when they should be fighting me". More importantly, the Conservatives are split over the same big themes that tore Labour apart. The rows about Europe and modernisation are familiar. Less well known is the division over tax and spend, the issue that virtually killed off Labour in a run of general elections. Mr Duncan Smith hails his tax-cutting agenda, although he is not precise about where the cuts in spending will fall. In contrast, the former shadow Chancellor Francis Maude has declared that the Tories should rule out tax cuts for the next parliament. Mr Maude knows about the dangers of promising tax cuts, having been a close ally of Michael Portillo during the era of Mr Hague's tax guarantee. As shadow Chancellor Mr Portillo rightly sought to give the tax guarantee some credibility by making it less of a guarantee and not necessarily anything to do with tax.

The timing of the Conservatives' latest bout of feuding is utterly perverse. Their focus – and indeed our focus – should be on a government that is in danger of tearing itself apart over the public services. In April a politically sensitive tax rise is being implemented to pay for improvements in the NHS. And how do ministers respond? They throw darts at the Chancellor and hint at unworkable policies that threaten to undermine the NHS. How odd that ministers were docile when Gordon Brown was imposing rigid spending controls and now, when he is delivering vast sums for their departments, they affect a divisive machismo. An almighty row is brewing over the future of the public services, over differing ministerial interpretations about what is required to be "bold".

Coincidentally, Mr Duncan Smith is in trouble partly because of his own attempts to appear bold, sacking those he disagreed with, taking on sections of his party. Unfortunately for the Conservative leader he cannot be strong when his own position is so weak. His affectations of boldness make him weaker still, fatally weak.