Gordon Brown, named leader of Britain’s ruling Labour Party, is seeking to convince voters that he represents a clean break with Prime Minister Blair’s government.

“This week marks a new start,” Mr. Brown told party activists in Manchester, England, on Sunday when he was elected unopposed as their leader. “Don’t let anyone tell you the choice at the next election will be change with other parties and no change with Labour. We will meet the challenge of change.”

Mr. Brown, 56, will take office as Britain’s prime minister on June 27 after Mr. Blair steps down. With Labour neck-and-neck with the Conservative Party opposition in polls, Mr. Brown, who spent the last decade as Mr. Blair’s finance minister, is seeking to persuade people that his agenda will revive the government’s popularity.

Taking aim at the biggest concerns of the electorate, Mr. Brown said he will appoint a housing minister to coordinate a new building program and make property more affordable. He promised to hand Parliament powers over war and to consult more often with voters about policy. The fight against terrorism, he said, will shift from the military to a battle for “hearts and minds.”

The Conservatives responded by blaming Mr. Brown for a surge in the cost of property. House prices have tripled since 1997 and increased more than 10% in the last year, according to HBOS Plc, the nation’s biggest mortgage lender.

“Housing has been the Blair government’s biggest domestic policy failure,” Michael Gove, a Conservative member of Parliament who speaks on housing policy, said in a statement. “Gordon Brown must share responsibility for this housing crisis. It cannot be solved by command and control from the center.”

A survey yesterday suggested Labour’s popularity pulled ahead of the Conservatives for the first time this year as Messrs. Brown and Blair worked together on an orderly transition. Mr. Blair said in September 2006 that he would step aside this year. He named his retirement date last month.

About 39% of voters would cast their ballot for the Labour Party if an election were held now, compared with 36% for the Conservatives, according to the Ipsos Mori poll. The survey of 1,970 adults was carried out between June 14 and June 20. No margin of error was given.

Under David Cameron, the Conservatives have led in every poll except three of the 83 surveys published between the end of March 2006 and Sunday. Mr. Blair, who won three elections for Labour since 1997, suffered declining popularity since he backed the war in Iraq in 2003.

Mr. Brown can govern as prime minister until the life of the current Parliament runs out in mid-2010, though he can request an election earlier. He will consider calling an election next year if polls point to a Labour victory, the Times newspaper reported, citing unidentified Mr. Brown aides.

Mr. Blair said at the conference that Mr. Brown is “a man with every quality to mark him out as a great prime minister. I know from his character that he will give of his best in his service of our country.”

Setting out his own vision, Mr. Brown said government was about “more than a set of policies — we must have a soul.” That remark resonated with the pledge of Mr. Blair’s first foreign secretary, the late Robin Cook, to enact ethical policies.

Mr. Brown acknowledged that Iraq had been “a divisive issue for our party and our country.” He signaled British troops will remain in Iraq and Afghanistan, at least in the short term, promising to “meet our international obligations.”

In the future, Mr. Brown said he will rely on international organizations, especially the European Union, to build “the strongest multilateral response” on issues including terrorism and the environment. Parliament, he said, will be given the power to decide whether to go to war and to check government authority.

“To isolate and defeat terrorist extremism now involves more than military force,” Mr. Brown said. “It is also a struggle of ideas and ideals that in the coming years will be waged and won for hearts and minds here at home and around the world.”

Labour Party members said Iraq will remain a drag on the government’s popularity ahead of the next election, which must be held by mid-2010. Mr. Brown appointed Transport Secretary Douglas Alexander to organize the election campaign, declining to give a signal on when the poll might be called.

“He hasn’t come to terms yet with the necessity of withdrawing the troops from Iraq,” Walter Wolfgang, a Labour National Executive Committee member who heckled Mr. Blair at the party conference in 2005, said in an interview. “The pressure to get the troops out has to be redoubled.”

John Denham, who resigned from Mr. Blair’s government over the Iraq war, said Mr. Brown “set out the values that are going to guide him” and that “there was plenty there to give us shape for the future.”

Harriet Harman, 56, beat five other contenders in the race to replace John Prescott as deputy leader of the Labour Party. Ms. Harman will serve as chairman of the Labour Party under Mr. Brown. She is a justice minister married to Jack Dromey, the deputy general secretary of the Transport and General Workers’ Union, who is seeking to become a Labour member of Parliament.

Ms. Harman has called for a review of the decision to renew Britain’s Trident nuclear missile system. Mr. Brown seemed to reject that call Sunday when he pledged to “take the tough decisions to ensure the long-term defense and security of our country.” Ms. Harman, who said she made a mistake in voting for the Iraq war, suggested the troops should stay there for now.

“You want us to acknowledge the anger and division caused by Iraq,” Ms. Harman said. “We must give our total support to our armed forces as they support Iraq’s fragile democracy.”