Michael Brown: Darling is disastrous but his argument is plausible – the Tories must up their game

In autumn the Tories won the argument but focus groups said their message scared voters

In theory the Tories hold all the aces. In practice, although Alistair Darling holds an apparently dreadfully bad hand of low-value cards, it seems to consist entirely of trumps likely to be played to potentially devastating effect against the Tories in the six weeks leading up to polling day.

I have never doubted – until now – my long-held prediction that Mr Cameron will ultimately win an overall majority of around 30 seats on 6 May. At the beginning of this week, in the aftermath of the Byers/Hoon/Hewitt scandal, I was convinced that a game-changing moment had occurred to the Tories' advantage. That may yet still be the case but I was amazed that yesterday's opinion polls showed a continuing narrowing of the gap between the two main parties.

But if the public reaction over the antics of the disgraced former cabinet ministers fades and is replaced by a greater interest in the fallout from the budget then it is clear that it will be "the economy, stupid", and not Labour sleaze, that will be the clincher when voters pass their judgement. My own knowledge of government finances is limited to Margaret Thatcher's "handbag" style of economics. The country is bankrupt.

The government debt, if not addressed immediately, will result in a collapse in the value of the currency leading to penal interest rates and another recession. The funny money created by the printing press is bound to increase inflation and all this will cause another recession. Even those with planet-sized brains in the Tory hierarchy probably agree with my O-level economics analysis. But they have yet to get this message over to voters and time is running out.

Yet, in his "Mogadon man – aka Geoffrey Howe" understated style, Alistair Darling made a plausible case for his utterly implausible argument as to why we should continue to rack up the national credit card and take no immediate steps to deal with the consequences of his predecessor's recklessness. Why on earth Gordon Brown thought Ed Balls should ever replace Mr Darling I cannot imagine. If anyone has the power to salvage the battered reputation of this rotting administration it is the boring reassurance of the current Chancellor.

By comparison, David Cameron's Commons knockabout response sounded somewhat chaotic. It was rushed and polemical. There were the usual one-liners and crowd-pleasing jokes for the benefit of his backbenchers. But it was not a vintage performance and left me wondering whether he, let alone the voters, actually understands Tory economic policy.

In fairness to the Tory leader it would be wrong to judge whatever his party's alternative proposals turn out to be on the basis of Mr Cameron's speech. Last autumn's pre-budget report was answered far more effectively by George Osborne, who is, admittedly, better able to get inside the details of Treasury minutiae. Neither was this the occasion, anyway, for Mr Cameron to set out the Tory alternative. That will doubtless now await the publication of their manifesto after Parliament has been dissolved.

My fear is that Mr Darling's case for delaying future necessary cuts – utterly misguided – is, however, based on a plausible argument. This may appeal to enough voters similarly unwilling to face up to what is about to hit them if they were to suffer the consequences of five more years of Labour economic mismanagement. And there was just enough to send Labour MPs, facing defeat in marginal constituencies, out onto the doorstep with ammunition to scare grumpy former Labour voters back into the fold.

Admittedly such ammunition amounts to no more than slings and arrows. But while the Tories should be able to assault Labour with massive firepower, they seem scared of their own shadows and unable to spell out a coherent argument as to why voters should chuck these irresponsible rascals out.

Last autumn the Tories successfully won the argument that Britain is bust and, notwithstanding the international banking crisis, public finance profligacy was down to Gordon Brown's "no more boom and bust" economic mismanagement. But then, in thrall to the voodoo politics of their wretched focus groups, they were told they were scaring voters with an over-austere message leading to inconsistency and a blunting of their message.

In recent weeks Labour have successfully implanted in the minds of voters that if teeth have to be extracted from the body politic, Mr Darling and Mr Brown might just be better dentists than Mr Osborne and Mr Cameron "of course there will be pain but we've got steadier hands and won't hurt you quite so much".

All this puts heavy pressure on the Tories to refine and simplify their message. The Tory website Conservative Home has suggested a way of relating the burgeoning deficit to individual families. They drafted a poster for the Tories suggesting that if things carry on as they are, borrowing rates will inevitably rise, causing mortgages to cost an average home-owner maybe an extra £1,440 a year. It is time for the Tories to stop talking in abstract terms about macroeconomics and put the spotlight instead onto household economics.