London ? David Cameron, whose boyish good looks and media savvy remind many of the youthful Tony Blair, was chosen leader of the Conservative Party on Tuesday, bringing new optimism to a party plagued by three straight election losses.

Cameron, 39, derided the prime minister and his government as “yesterday’s men” and pledged to sweep them aside.

“We have a vast mountain to climb,” he said, joined by his wife, Samantha. “But if we are united, if we have a clear view about what needs to change … we can be a constructive opposition and we can be that good government that this country clearly needs.”

His rival, David Davis, who was trounced in the ballot of party members by more than two votes to one, conceded defeat and heralded Cameron as a Conservative prime minister in waiting.

After the Conservatives’ crushing election defeats, Cameron faces the challenge of leading the party back from the political wilderness.

Led by political giants such as Winston Churchill and Margaret Thatcher, the Conservatives dominated the 20th century but are now viewed by many voters as out of touch with modern, multicultural Britain.

Choosing Cameron to broaden its appeal is a risky move. The son of a stockbroker, he attended the elite private school Eton and is a graduate of Oxford University – a background the well-spoken leader acknowledges is “hideously privileged.”

His wife is the daughter of a baronet. According to Debrett’s Peerage & Baronetage, Cameron is a descendant of King William IV – through the king’s illegitimate daughter. That would make him a fifth cousin twice-removed of Queen Elizabeth II.

But he has a common touch, listing his favorite bands as Radiohead and The Smiths, going to work by bicycle and refusing to say whether he took cocaine as a student, declaring he is entitled to a private life before entering politics.

His son Ivan, 3, suffers from severe cerebral palsy and epilepsy – shaping his strong support of specialist schools for handicapped children. His daughter, Nancy, is nearly 2. His wife is pregnant with a third child.

For the Conservatives, this is an opportune time to take on Blair.

The prime minister’s grip on power appears weakened, his popularity remains in a slump over the Iraq war, and a rebellious band of his own lawmakers are clamoring for him to step down in favor of his Treasury chief, Gordon Brown.

But Blair and his likely successor, Brown, still pose a formidable challenge for Cameron as he builds for elections expected in 2009. He has just four years’ experience as a lawmaker, compared with Blair and Brown, both in politics more than 20 years.