John Rentoul: The handbrake turn that kills Prudence

Usually, "how would you vote if there were a general election tomorrow?" is a hypothetical question. Last week, it felt a little less so. On Monday, the two main parties engaged in competitive scheduling to try to hold the earlier news conference: David Cameron at 8.30am, Gordon Brown at 9.30am.

On Wednesday, we had a bitter party political spat at Prime Minister's Questions over an emotive social issue of the kind that sometimes disrupts election campaign planning grids. And this weekend the Prime Minister used a foreign trip to give his domestic reputation such a shine that he could see his reflection in it.

Our ComRes poll today is, therefore, more of a real-world simulation than such surveys often are, and an 11-point lead for the Conservatives calibrates the Brown Bounce as real but not enough to warrant a 2009 election. One top Tory told me: "After 'Gordon is God', I thought we would have been further back in the polls."

Cameron says he is not complacent, and I believe him. He and Steve Hilton, his strategic adviser, sometimes describe themselves as "children of 1992". That was the election campaign in which they cut their teeth as twentysomething Tory staffers. It was a campaign that proved two things: that governments can win elections in downturns, and that the opinion polls can be wrong.

If today's poll is right, however, it contains two worrying messages for Cameron. One is that 57 per cent of voters are not inclined to blame Brown for rising unemployment. That cuts against what Tory sources describe as their objective of "pinning the tail on the donkey", as they try to make sure the Prime Minister pays the price for the poor state of public finances. Senior Tories point to poll findings which suggest that voters think Brown's policies have contributed to the recession, but today's ComRes survey says that they don't think the Prime Minister should take "most of the blame" for job losses.

The other worrying finding is that half the sample agreed that Cameron's team is "lightweight". Cameron is aware of the problem. I understand that Kenneth Clarke and Norman Lamont took tea with the Tory leader the other day to lend a bit of economic bottom to the Opposition effort. Nigel Lawson and John Major, fellow members of the Tory former chancellors' club, and Lord Burns, the former Treasury permanent secretary, now advising the Tories, all recently laid into the policy of borrowing to pay for tax cuts, which Brown and Alistair Darling seem poised to adopt.

Here is the nub. Our poll suggests that the Conservatives have public opinion firmly behind them: 75 per cent agree that "tax cuts should be paid for by the government spending less rather than borrowing more". But something strange is happening in the land of economic theory.

When Brown said at his Monday news conference that the Tory plan for tax cuts was no good because they were paid for by public spending cuts, I thought of Alice Through the Looking-Glass. Previously, he attacked the Tories because they hadn't said how tax cuts would be paid for. Now, though, he seems to believe that borrowing to put cash in voters' hands is the way to stimulate economic activity and mitigate the recession.

This inverts the orthodoxy that Brown persuaded the Labour Party to accept at some personal cost in the early 1990s. Yet Paul Krugman, the Nobel prize-winning economist who praised the Prime Minister last week for "setting the template" for the global response to the credit crunch, has gone Through the Looking-Glass too. On Friday he wrote in The New York Times: "When depression economics prevails, the usual rules of economic policy no longer apply: virtue becomes vice, caution is risky and prudence is folly."

Prudence is folly! In other words, the guiding principle of Brown's economic policy has just swivelled 180 degrees. In order to be prudent now, governments are required to do what would have been utterly reckless not many months ago.

Last week, two of the cleverest economists on the planet, Krugman and Gavyn Davies, said that the global situation was so serious that economic orthodoxy must be stood on its head. Davies said that governments should print money, a "crazy and dangerous procedure" in normal times but necessary if the outlook for the global economy "weakens only a little further than is now feared".

If Darling can make a credible case for this approach in the pre-Budget report, public opinion may change. (Next week's event used to be called the Autumn Statement, but this was changed in a fit of political correctness gone mad in order to avoid offending those suffering from Seasonal Affective Disorder.) Brown and Darling have yet to step fully into the Looking-Glass world of what Krugman calls "depression economics". Brown is, after all, a cautious politician. The trouble is that Krugman now defines caution as risky. And the other problem is that Darling is even more cautious – or even more risky, depending on which side of the mirror you are on. In his interview in The Independent last week his tone was different from Brown's: he emphasised that "you live within your means".

So, who is right? The Tory former chancellors and former Treasury mandarin on one side, or Krugman and Davies on the other – or Mervyn King, the governor of the Bank of England, who hedged his bets in the middle with careful talk of a "temporary" fiscal stimulus on Wednesday? That is the big decision in the pre-Budget report in eight days' time.

It is a decision that could tip the scales of the next election, still probably 18 months away, despite last week's rehearsal. Already, the scales are more evenly balanced than they have been for most of the past year. I agree with my estimable colleague Alan Watkins, who writes on page 45 that they are still tilted against Brown. But where there was nothing in the credit pan of the scales before, now there is the heavy weight of his handling of this crisis. It may not be enough, but it is different from what went before.