By Michael Portillo
David Cameron's great achievement has been to move the Conservative Party on to the centre ground, which New Labour had monopolised for a decade.
He has faced down those in his party who saw that as a sell-out.
Some critics have urged him to be bold and radical, like Margaret Thatcher.
David Cameron "knows that spending needs to be pruned"
In recent weeks, the political game has changed. We are at a historic turning point. At one time Cameron made little distinction between his economic plans and Labour's.
But with the deterioration in the public finances, now he wants to distance himself from the government's failures.
But how big a gap should he open up?
Mrs Thatcher faced a similar dilemma in 1979. Then too, Labour presided over economic catastrophe and it seemed that radical measures were required.
Indeed, the crisis provided her with a welcome opportunity to be radical as she longed to be.
But she knew that the British public is easily scared. So before that election she was ultra cautious. She promised only gradual reform and did not even mention privatisation.
Cameron today knows that public spending needs radical pruning.
Indeed, it might be a welcome opportunity to reduce the size of the state and to be much tougher on those who should be working, not claiming benefits.
But should Cameron come out and say so?
If he does, Gordon Brown will allege that he cannot be trusted with schools and hospitals. If he doesn't, why should the public think that the Tories will manage the economy better than Labour?
And what about the Chancellor's new 50p top rate of tax? If Cameron promises to scrap it, Brown will sneer that he wants only to protect the Tories' rich friends.
But if he doesn't make that pledge, supporters will wonder what's the point in having a Conservative government?
And since Cameron, like Thatcher, surely thinks high taxes bad and wrong, isn't it only honest to say so?
There is Cameron's dilemma. Is it time to abandon his cherished centre ground and become a radical?
Well, while he thinks that one through, he'll be careful not to be misled by fuzzy and inaccurate memories of Margaret Thatcher.
She put winning office for the first time above all else. Before that first election win she was moderate to a fault.
But after three terms in office, that's not exactly how the world remembers her.