Cameron, 39, won his post Tuesday on a wave of excitement and high expectations within the party, which is now on its fifth leader since Blair swept into power in 1997.
The Conservatives' long-demoralized supporters believe this time is different.
They're desperate to see Cameron take advantage of Blair's sagging popularity and lead them to back to power after three straight election defeats. And they believe he has the same traits: youth, vigor and political savvy that helped the prime minister lead the Labour Party to office.
Cameron says the Conservatives, widely seen as stodgy and traditionalist, must remake themselves if they want to connect with voters.
"No more grumbling about modern Britain," he said after his lopsided victory over leadership opponent David Davis. "I love this country as it is, not as it was, and I believe our best days lie ahead. ... I want us to give this country a modern compassionate Conservatism that is right for our times and right for our country."
He acknowledged that the Tories have a tough job ahead, but said they could win the election expected in 2009 if they unite and move to the center.
The party, led by political giants such as Winston Churchill and Margaret Thatcher, dominated the 20th century but is now viewed by many voters as out of touch with modern, multicultural Britain.
The boyish-looking Cameron says his centrism and concern for issues like inner-city poverty and women's representation in Parliament will make the Tories relevant to voters again.
In an acceptance speech reminiscent of some of Blair's own addresses, he spoke of boosting public services like health and education, tackling global warming, protecting national and international security and improving the plight of pensioners.
"We have to change in order for people to trust us," he said.
Educated at the exclusive English private school Eton and Oxford University, and married to the daughter of a baronet, Cameron says his background is "hideously privileged."
His opponents argue he lacks experience, since he has only been a member of Parliament since 2001.
But he is steeped in Westminster politics. He joined the Conservative research department in 1988, worked as a special adviser for former Finance Minister Norman Lamont and helped Prime Minister John Major prepare for parliamentary debates in the mid-1990s.
His son, Ivan, 3, suffers from severe cerebral palsy and epilepsy and Cameron has strongly supported specialist schools for disabled children. His daughter, Nancy, is nearly 2, and his wife, Samantha, is pregnant with their third child.
The Conservatives believe this is an opportune moment to challenge Blair.
The prime minister's grip on power appears weakened, his popularity remains in a slump caused by the divisive Iraq war, and a rebellious band of his own lawmakers are clamoring for him to step down in favor of his powerful Treasury chief, Gordon Brown.
Cameron's appointment as leader marks a pivotal moment for the Conservatives, who were knocked from office in 1997 after 18 years in power. They have yet to fully recover from the trauma of the infighting that pushed Thatcher from office in 1990.
The center-right party has grappled for a sense of direction — unsure whether to stick with its traditional low-tax, free-market agenda or boost investment in public services and build a strong welfare state.
Like Blair, Cameron wants to combine both approaches, lead from the center and blend social conscience with the ethos of the free market.