David Cameron has told Conservatives to be the party of optimism, urging them to "let sunshine win the day".
In his first conference speech as leader, Mr Cameron conceded that the party had alienated voters by "banging on" about Europe and tax cuts.
And he rebuffed calls from within the party to commit to tax cuts.
The party must claim the political centre ground and become the champions of a "new spirit of social responsibility," said Mr Cameron.
It must also trust ordinary people to make decisions about their own lives, said Mr Cameron.
And it must focus on the issues which concern voters, like childcare, standards in state schools, a better NHS and low mortgage rates, he added.
Speaking against a backdrop of green foliage and bright sunlight, he told delegates: "Our party's history tells us the ground on which political success is built."
"It is the centre ground. Not the bog of political compromise. Not the ideological wilderness, out of the fringes of debate. But the solid ground where people are."
Mr Cameron, who received a one minute standing ovation, faces a challenge to his plans on Monday from John Redwood, the chairman of his competitiveness taskforce, who will publish a pamphlet calling for big tax cuts.
Mr Redwood, chairman of the Thatcherite No Turning Back group, claims the backing of more than 50 Tory MPs for a document arguing the case for lower taxes and the "moral justification" for doing do.
The Conservatives' Tax Reform Commission set up last year under previous leader Michael Howard is expected to call for £20bn in tax cuts - mainly in income and inheritance tax - when it reports later this month.
But speaking earlier on BBC One's Sunday AM, Mr Cameron said he would not be rushed into making policies.
"Those people who say they want tax cuts and they want them now - they can't have them," said the Tory leader.
It follows an attack by Mr Cameron on Chancellor Gordon Brown, the frontrunner to be the next prime minister, who he claimed in the Sunday Telegraph was "tragic" and "being pushed around by everyone".
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Mr Cameron was preceded in the main hall by US Presidential hopeful Senator John McCain, who hailed his "able and determined" leadership.
Mr McCain paid tribute to the "unity, confidence and principled sense of purpose that distinguishes British Conservatives under the leadership of my friend David Cameron".
He also warned of a "dangerous, difficult and long fight" against Islamic terrorism but insisted America, Britain and their allies would prevail.
Mr McCain won loud applause from Conservative activists in a packed hall when he insisted "government that governs best, governs least".
Environment Secretary David Miliband later gave his reaction to Mr Cameron's big speech.
"Today's speech again confirms that when you get beyond the image and PR, David Cameron does not have the policy answers to the challenges the country faces.
"Empty rhetoric and vacuous slogans are not enough.
"The fact is that until David Cameron begins to back up his warm words with concrete and workable policy commitments, people will conclude that the Tories are all style and no substance," said Mr Miliband.