Analysis By Nick Assinder Political correspondent, BBC News website

What does David Cameron really believe in, isn't he just copying Tony Blair and is he a Conservative at all?

Mr Cameron has highlighted EU policy

According to the Tory leader himself, these are some of the questions he is regularly asked by party activists - sometimes in unprintable language - and that he is now set to answer.

Until now there has been a widespread suspicion that this lack of clarity in some areas was deliberate - that he was engaged primarily in an exercise to win over Labour voters fed up with Tony Blair, without scaring them off with talk which might remind them of the Tories of old.

That has led to claims from critics within his own party that he has overdone the soft, liberal talk - the "Polly Toynbee" or "hug a hoodie" effect - and risked turning away core Tory voters.

As if to underline the point, just as Mr Cameron was attempting to address those concerns, senior party supporters were threatening to switch to the UK Independence Party in protest at his "soft" approach to Europe.

Two Tory peers joined UKIP last week and now a major donor to the party, spread betting tycoon Stuart Wheeler, and former party treasurer and Dixons founder, Lord Kalms, have threatened to switch their support to the party.

Blair-lite

Mr Wheeler summed up the fears of many on the Eurosceptic wing of the party when he declared: "I think Cameron's done a tremendous thing for the Conservative Party and I would very much rather the Conservatives form the next Government.

Tory leader claims he looks more to Thatcher than Blair

"One side of me says I don't want to do anything to upset that. On the other hand, I think the Conservatives have not been nearly strong enough on Europe."

It is no surprise those attacks have come from Eurosceptics, but similar sentiments can be heard from other traditional Tories on issues like law and order and taxation, for example.

Until now, Mr Cameron has appeared relaxed about such attacks - apparently welcoming some of them as proof he really was modernising the Tories.

Even suggestions he was offering a "Blair-lite" government-in-waiting appeared not to bother him.

But he now seems to have shifted emphasis. In an article in the Daily Telegraph he has rejected the "Tory Blair" tag, suggesting he is really the heir to Margaret Thatcher and that it is Chancellor Gordon Brown who is doing the apeing - of his new Tory agenda on personal responsibility, the environment and so on.

And, perhaps accepting the argument that the last thing voters will want after Tony Blair is another one, he declared: "The modern Conservative Party is about replacing the failed New Labour experiment, not apeing it".

Keeping the pound

Explaining his belief in Thatcherite ideas, he added: "Those ideas are profound and enduring: freedom under the law, personal responsibility, sound money, strong defence and national sovereignty."

Tories would not join single currency

If that sounds like a list that just about any party or voter could sign up to, he went on to stress his support for the family, his taxation and spending plans and, pointedly, his opposition to the single European currency that mark out clear differences from Labour.

His new emphasis on Europe, which also includes restoring the opt-out from the social chapter, withdrawal from the European People's party, opposing the constitution and keeping the pound, is clearly aimed at Euro doubters in the country as much as his party critics.

He can weather a few defections, particularly by individuals who still claim they want the Tories to win the next election, but he cannot afford to lose voters in any number.

So the underlying suggestion will be that those defectors are not simply demanding a tougher line on Europe - which he claims he is already offering - but that they have a secret agenda to pull Britain out of the EU altogether.

On wider policy, however, he may still not have said enough to persuade his critics he really is the new Thatcher rather than the next Blair.

He was selective in the bits of the Thatcherite agenda he chose to praise - specifically her vision of the "good society" rather than the "no such thing as society" comment - which might not reassure all on the right of his party.

Still, Mr Cameron has promised that 2007 will be the year in which he will set out concrete, coherent and modern polices to answer all his critics.

It is a year which could prove crucial to Tory fortunes.