New Conservative Party leader David Cameron cast himself Wednesday as the face of Britain's political future and portrayed Tony Blair as a has-been in his first confrontation with the prime minister since being elected head of the Tories.

Conservative lawmakers roared as a confident-looking Cameron stood up during the prime minister's weekly question-and-answer session in the House of Commons. He grinned when Blair congratulated him on winning the leadership post.

The new Tory leader, 39, then immediately began needling Blair, 52, portraying himself as the young face of optimism and the prime minister as a man of the past.

"This approach is stuck in the past and I want to talk about the future," he said after Blair noted a disagreement in their positions on school reform. "He was the future once."

The half-hour session was seen as the first big test for Cameron, who on Tuesday became the Tories' fifth leader since they last won an election in 1992.

The party faithful hope his youth and charisma will help them reconnect with voters and recapture power after years spent struggling to regain their footing. Some have likened him to a young Blair, who took the Labour Party's helm at 41 and made it an election-winning juggernaut.

Cameron quickly sought to make good on his promises to overhaul the Conservatives' image, focusing one of his first questions on the environment, an issue not normally associated with the party.

Blair brushed away Cameron's query, accusing the Conservatives of voting against concrete action to deal with global warming.

"It is important not merely that we say how much we care about climate change but that we take the action necessary," Blair said.

The weekly opportunity for lawmakers to question the prime minister at the House of Commons produces more knockabout theater than reasoned exchanges, but it is an important showcase for party leaders.

Three years ago, Cameron described his palms sweating and his heart pounding when, as a newly elected lawmaker, he rose to ask his first question of Blair from the back benches.

"Why all the excitement?" he asked in a column for the Guardian newspaper in May 2002, a year after he entered Parliament. "It is the only time you rise to your feet when the chamber is packed — and baying for your blood."

The Guardian reprinted the piece Wednesday.

Cameron appeared more confident Wednesday, but the pressure will remain high as Britons watch to see whether he looks like a potential prime minister.

He succeeds Michael Howard, a Tory veteran known as one of the party's best verbal jousters and widely praised for his performance in the weekly face-offs with Blair. Cameron will face a daunting opponent in Blair, who is far more experienced and renowned for his debating skills.

Conservatives are eager to see their new leader take advantage of Blair's sagging popularity and reinvigorate a long-demoralized party after three straight election defeats. They believe he will make a tough opponent to Treasury chief Gordon Brown, who is widely expected to succeed Blair before the next election, likely in 2009.

Cameron says the Conservatives, seen by many as stodgy and traditionalist, must remake themselves if they want to return to power.

"We have to change in order for people to trust us," he said after his overwhelming victory over leadership opponent David Davis. "No more grumbling about modern Britain. I love this country as it is, not as it was, and I believe our best days lie ahead."

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.

A poll commissioned by the British Broadcasting Corp., released Wednesday, found that voters are more likely to trust Conservatives on issues of crime and education but more likely to trust Labour on the economy, health, environment, family policy, the European Union and immigration.