John Rentoul: Blair's Middle England solutions offer no way out this time

It's what politicians don't say that tells you most about them. George Osborne gave a loud – I wouldn't say confident – response to the mini-Budget, a response that roused Tory MPs, who sensed a government in trouble, even if they suspected during the quiet bits that a Conservative government in the same place would have done exactly what Alistair Darling had just announced. Vince Cable pointed out that Ken Clarke, Osborne's main rival for the post of shadow chancellor, had advocated a temporary VAT cut even before the Government leaked its policy to the Sunday newspapers.

So Osborne concentrated his effort on the I-wouldn't-have-started-from-here gambit. He took Gordon Brown apart for having put the nation's finances in such a weak position. On that, everyone can agree, if they think about it. But the trouble is that such a vast borrowing splurge adds only one-fifth or so to the even vaster borrowing splurge that was already in progress, and so doesn't look as bad as if we were starting from a balanced budget.

And that attack is backward-looking. More fruitful is the tax timebomb line. Everyone knows that borrowing now has to be paid for later, and Osborne's claim that Brown "thinks he can borrow his way out of debt" was vivid. But it hardly amounts to an economic argument about why it is right to borrow £100bn but wrong to borrow £120bn. Especially when Ken Clarke agrees with the Government.

But what Osborne failed to mention in his reply was the plan for a higher rate of income tax, 45p in the pound on incomes of more than £150,000 a year in 2011. When a politician doesn't mention something important such as that, you know he has been ambushed. When it had been leaked to that morning's newspapers, you know he has been so taken by surprise he still hasn't thought of the right answer. Which is, incidentally, "We should have thought of it first".

It is all very well David Cameron wanting to be the heir to Blair. Who wouldn't, after all, want to win three elections? And it was Blair who told this newspaper, in 2001, why he would not put a higher rate on higher incomes: "It may warm the cockles of some political activists if you go after the very wealthy, but I think it is a misplaced use of political energy. Even if you were to do it, the benefits you might yield ... could be outweighed by the signals you would send out."

But the signals sent out now are rather different. Gordon Brown told the CBI he was "leaving behind the orthodoxies of yesterday". These did not include, sadly, such wisdom passed down by the father of the manse, "a stitch in time saves nine", that he divulged to Radio 2 listeners on Friday. They include, on the contrary, every assumption about economics or politics that has ruled since at least the time of James Callaghan. So, as Paul Krugman, the Nobel Prize-winning economist, told us this month, prudence is folly. Debt is good. What reassured Middle England in '97, '01 and '05 is now old hat. In times of austerity, what Blair called "the very wealthy" must bear their share. After all, it worked for Barack Obama, whose vote-to-income ratio was U-shaped: the poor voted for him, as did the very rich.

Will it work here? Like the pre-Christmas discounts, I suspect, "for a limited time only". No wonder Brown will not rule out an early election. I suspect he may come to regret his ad lib on Sunday's BBC1 Politics Show, when he said: "I am not planning it at all; I do not think people would think much of me."

John Rentoul is the chief political commentator for The Independent on Sunday