Youthful David Cameron promised to "switch on a whole new generation to the Conservative Party" as he made a confident pitch for the party leadership yesterday.

At 38 - his birthday is Sunday - critics claim he is too young and inexperienced to lead.

But Mr Cameron made a virtue of his fresh face, telling Tory activists a "young, passionate, energetic leader" might not be a bad idea.

He said he wanted people to "feel good about being Conservatives again". And his speech, not lacking in passion or energy, was rewarded with an enthusiastic three-minute ovation.

Despite his recent promotion to the role of shadow Education Secretary, he is less well known to the public and Conservative Party members than David Davis, the bookies' choice.

And his profile is lower than Ken Clarke, who also spoke yesterday.

But Mr Cameron's supporters have long insisted the more people get to see their man, the more they will like him. Yesterday's speech was make-or-break for Mr Cameron. And there was an added pressure.

If he doesn't win, he can try for the party leadership next time. For Mr Davis and Mr Clarke, this may be their last chance. But the way he conducts himself now will be remembered by fellow MPs and party members.

Mr Cameron gave a brutal assessment of the Conservative performance at the last election. Labour, he said, had "dumbed down the education system, demoralised the health system, and bankrupted the pension system . . . It's made promises that no-one believes."

But the Tories still couldn't win. He told delegates: "Let's have the courage to say, they've failed - but so have we. We must look ourselves in the eye, and make this pledge - never, ever, again."

He gave delegates a taste of his passionate style, in a heartfelt section dealing with education.

Mr Cameron, the father of a severely disabled son, condemned Labour for closing special schools.

"Labour's idea of compassion is to put every child in the same class in the same school - and call it equality and inclusion. But I say that's not compassion. It's heartless, it's gutless and it's got to stop."

But he warned the party couldn't assume it would get the chance to put principles into practice.

"There are some people who say, 'all we've got to do is wait for the economy to hit the rocks, for Gordon Brown to be more left-wing than Blair. All we need is one more heave'.

"I think that's a pathetic way for a great party to behave. One more heave means one more defeat."

He added: "Let's give Gordon the fight of his life."

To do this, the party had to change, he said. The party needed a message relevant "to the people living in our inner cities, of all races and religions, grappling with the problems caused by family breakdown, poor housing and low aspirations.

"We know we have a shared responsibility; that we're all in this together; that there is such a thing as society - it's just not the same as the state."

Changing the party would be "a wonderful journey", he said. But he urged Conservatives: "Come with me."