Matthew Norman: Cameron can't afford mistakes. But nor can he play it safe

The Tory leader is walking a tightrope without the flimsiest of safety nets

As general election slogans go, this is the one that dare not speak its name. We will neither hear it from the oddly sensuous lips of the Prime Minister, nor watch it alternate with adverts for any car manufacturer still in business on one of those perpetually rotating giant posters. Even so, the message Gordon Brown will tacitly but relentlessly feed us between now and the next election is "You've Never Had It So Bad".

Ordinarily, noting how Mr Brown's absolute reliance on sustaining public terror about the economy makes him the diametric reverse of Harold Macmillan, the temptation would be to christen him SuperCam. This we cannot do, of course, Cam being the outmoded, pre-Dave nickname for an Opposition leader for whom life becomes less super all the time. In our new bizarro world, where every tenet of conventional wisdom is turned on its head, it is the incumbent who prays for doom and gloom while the insurgent sinks to his knees and begs the Good Lord to make things better.

Alas, alas and thrice alas for David Cameron, the Almighty shows no sign of listening and, with each fresh report of climbing redundancies, mounting home repossessions and the burgeoning possibility of recession tipping into depression, his opinion poll lead contracts. The latest poll has it within the margin of error at a paltry three points and, as his advantage shrinks, so does Mr Cameron's own margin of error. He cannot afford the tiniest of mistakes, but nor can he play it safe.

A couple of months ago, he was waltzing, with a shade more elegance than dear John Sergeant, to a landslide. Today, he finds himself walking a tightrope without the flimsiest of safety nets. He must avoid even hinting at recklessness while gambling on a strategy that persuades the electorate he is as safe a pair of hands as Mr Brown. How his first major roll of the dice will land, it is too soon even to guess. Mr Cameron certainly unveiled his reneging on the commitment to stick to Labour's spending plans with confidence and aplomb, and delighted many within his party and the Conservative press. Presumably, he calculates that the benefit of shoring up core support when the Tory right is suddenly becoming restive again, and the mid- to long-term advantage from donning the Prudence McScrooge face mask discarded by the PM, will outweigh the damage done to his rebranding of the Conservatives as socially compassionate.

What makes no sense at all is his retention of George Osborne. The very fact that Mr Cameron, and not his shadow Chancellor, made the grand announcement on spending illuminates the extent to which Mr Osborne is diminished by the joyous tale of fin de siècle excess on Corfu. His joshing on the matter of super-yachts with the noble Lord Mandelson at a recent parliamentary awards lunch speaks well of his flair for gallows humour, but doesn't disguise that he remains the one swinging limply at the end of the rope.

For all his obvious talents, the unlucky little lamb has not one shred of credibility when that is the quality Mr Cameron needs above all others. Without it, and with the spectre of an early election flitting about again (God preserve us from another bout of that psychodrama from within No 10), he cannot hope to pull off the win double that is essential to regaining the initiative. He must both persuade a dubious electorate that the Tories are best qualified to mitigate the horrors of the coming years, and at the same time convince it that Gordon, far from being the Saviour of the Global Economy of his own styling, was the lead horseman of the Apocalypse – the phoney, faux-pious wastrel whose wildly profligate stoking of the credit- and house price-fuelled boom immeasurably worsened the impact of the bust.

This he cannot begin to achieve with a partner widely regarded as the Bullingdon buffoon who sipped Cristal with Rothchilds and Russian oligarchs while the inferno was being lit. Mr Cameron is saddled with a snigger-raising bantamweight at the precise moment he desperately needs a super-heavyweight, and on economic affairs there is only one of those among his parliamentary colleagues.

Whether Kenneth Clarke would accept the challenge, I haven't the foggiest. At 68, after so action-packed a career, it could well be that he is enjoying the languor too much to sacrifice it for one final hurrah. He has his lucrative directorships, his bird-watching with Hezza, Hurdo and the gang, and afternoons watching Nottingham Forest from the directors' box to amuse him.

A sensible near-septuagenarian would reflect on this, and on the rejections by his dim-witted party (understandably, the one in Iain Duncan Smith's favour rankles especially), and tell his leader where to stick it. Yet there is a healthy dash of insanity in even the sanest politicians, so who knows?

If he did take up the gauntlet, what a masterstroke it would prove for Mr Cameron to pluck the most popular and trusted Tory of recent decades from the backbenches and have him by his side. Speaking with the authority of the Chancellor who bequeathed the lavish legacy Gordon so rashly squandered, Mr Clarke would be as effective a rebuttal to the deadly charge of economic callowness as Joe Biden proved for Barack Obama on foreign affairs. He'd kick that nice Alistair Darling half to death, and mortify the Prime Minister too. The movement in the polls would be instant, vertical and sustained.

If Mr Cameron transferred Mr Osborne to the Home Office, allowing him more time to work on his glottal stops and estuarian timbre, and persuaded William Hague to become a marginally less semi-detached shadow foreign secretary, he would find himself heading as formidable an Opposition top table as any in living memory. At the very least, the return of Ken Clarke would surely scare Gordon out of any revived flirtation with a snap election.

Whether this is a realistic notion or merely fantasy politics, Mr Cameron urgently requires what the Americans call a game-changer. The volte face on spending plans won't cut it, however much it assuages traditional Tory support, because the game is not about policies (it will be years before their effects become apparent) but perceptions. So long as Gordon is perceived as the nurse and Mr Cameron as the something worse, those opinion polls will maintain their current trajectory, and the odds against You've Never Had It So Bad becoming the most inaudible and outlandish winning slogan in electoral history will narrow by the week.

Like Hamlet, the senior ministerial doubters can find always agonising reasons to delay rather than wield the dagger. In my view their reasons for delay in the autumnal whirlwind are sound, at least for now. Shakespeare's play is a long one. This drama has several acts left.