David Cameron has outlined his vision of a "modern, compassionate" Conservative Party, which he says will be a serious alternative to Labour.
Mr Cameron says it's time for change
Mr Cameron said the test for Tory policies would be how they helped the less well off.
By choosing a new leader the Tories had voted for change - and now they had to show what that change meant, he said.
The Conservative leader is to ask the party's 250,000 plus members to agree a new statement of its aims and values.
He said he was fed up with hearing the party was out-of-touch, lacking in compassion and backward looking.
'Time to be different'
The move is being likened to Tony Blair's decision to ditch Clause 4, his party's commitment to nationalisation.
Mr Cameron's predecessor Michael Howard also issued a list of core beliefs on taking over as Conservative leader, but he did not put the document to the vote.
AIMS AND VALUES:
Economic stability before tax cuts
Policies must help the least well-off, not the rich
Women's choices on work and home lives will be supported
Public services will not necessarily be run by the state
Party will fight for free and fair trade
Tories will be hard-nosed defenders of freedom and security
Government should support home ownership, saving, families and business
Government should be closer to the people
In a speech in London on Tuesday, Mr Cameron said the party had the right values for the challenges Britain faced.
But he insisted: "We know we have to change. I stood for the leadership because I'm fed up with hearing that this party is out of touch, backward-looking and lacks compassion.
"That's not the Conservative Party I'm leading.
"This party voted for change. Now we have to show what that change means. Not just what we're changing from, but what we're changing to.
"We have to show that the change is real, that it means something, that's it's built to last. That's why today I'm setting out, in this statement of aims and values, what we stand for and what we're fighting for."
'Built to Last'
Economic stability must come before tax cuts, public services must be improved for everyone and climate change had to be tackled on a cross-party basis, he said.
A policy document, entitled "Built to Last", will go out to consultation during the next few months. Party members will then be asked to vote on it.
Shadow foreign secretary William Hague said if he had tried to outline the changes Mr Cameron was calling for when he was Tory leader, they would have been "highly controversial".
"There would have been a lot of resistance to it - that shows how much the party is changing," he said.
"I didn't speak to an audience with this mix of age groups and backgrounds."
But ex-Tory chairman Lord Tebbit described Mr Cameron's new initiative as just "clever marketing", saying it was hard to see any differences with Labour.
The battle is on
However, Mr Cameron said there was a clear choice between the Conservatives' approach and Gordon Brown, the man who is widely predicted to be Tony Blair's successor.
He said as prime minister, Mr Brown would continue Mr Blair's "ineffective authoritarianism" and think public services could only be run by the state. He would also do or say little on the environment, he said.
Mr Cameron added: "If we don't change, we will let millions of people down.
"But if we do change, if we stick to it, if we show that it's built to last - then we'll be able to meet the challenges this country faces and help create a better Britain - built to last."