The political divide: Clear blue water is suddenly visible

Labour and the Tories disagree on how we got into the recession in the first place and how to get out of it. But on one thing they are agreed: there will be a real choice for the voters at the next general election.

David Cameron's announcement today that he is abandoning the Conservatives' promise to match Labour's planned spending up to 2011 has transformed the political landscape.

A sharp divide - what could be called clear blue water - has now opened up between the Tories and Labour on how to tackle the economic crisis.

Labour says it is prepared to spend its way out of recession. Borrowing will be increased massively to ensure that taxes are cut and spending increased now - and while taxes may have to rise later, the priority must be to get the economy moving again.

The Tories say that Mr Brown's borrowing spree will result in a "bombshell" of tax increases in the not too distant future when the books come to be balanced.

According to Mr Cameron. the country must learn to live within its means, even if means the recession will be tougher on families and businesses, so that there can be permanent tax cuts in the future.

Prudence, once Gordon Brown's much-admired partner when he was Chancellor, is now walking out with Mr Cameron. The Tory leader claims she was jilted by Mr Brown when things got difficult and is now back with someone who really respects her.

Meanwhile Mr Brown, who used to argue until he was blue (or was it red?) in the face that unfunded tax cuts would be the road to financial ruin, now claims with equal vehemence that a "fiscal stimulus" is the equivalent of the Holy Grail and the route to salvation.

The voters are likely to be confused by such shameless political role reversal. Not only did the speed and scale of the economic meltdown catch our political leaders unawares. It has also destabilised once were once regarded as the established political norms.

Both Mr Brown and Mr Cameron are beginning to resemble gamblers locked in a deadly serious poker game in which the country's future - not just their own political reputation - is at stake.

Mr Cameron is dismissive of what he describes as Mr Brown's new "father of the nation" guise.

He is banking on the voters being more prepared to trust a politician who "looks them in the eye" and tells them the truth, even though the facts may be painful. He wants to be seen as "honest Dave", regaining the Tories' traditional reputation for fiscal responsibility, which was lost in the trauma which followed Black Wednesday in 1992.

It is a huge gamble. The original decision to match Labour's spending plans was taken to close down what had become Mr Brown's refrain at the last three general elections: that Tory public spending cuts would lead to cuts in schools and hospitals - often accompanied by a helpful chart showing the impact of the so-called "cuts" in each constituency.

Mr Cameron insists the Conservatives will still be increasing public spending - but by a lower amount than Labour - and that is not a "cut". But that is an argument that is likely to be drowned out by a concerted Labour onslaught on the impact of a Tory squeeze on future spending.

His decision delighted Tory Right-wingers, who never liked or supported the promise to match Labour's spending plans. It will give George Osborne, the shadow chancellor, headroom to look for possible tax cuts, but it will make it even more difficult for the Tories to promise increased spending in priority areas such as defence.

The first test of the Tories' new financial stringency will come on Monday. Chancellor Alistair Darling is preparing to announce a pre-Christmas give-away in his autumn mini-budget. Will Mr Cameron and fellow Tories really want to be seen voting against tax cuts for hard-pressed families this winter?