Rob Griffith, Associated Press
Kevin Rudd, left, with his wife, Therese Rein, makes his acceptance speech Saturday in Brisbane following his victory as Australia's next prime minister.

SYDNEY, Australia — Conservative Prime Minister John Howard, one of the Bush administration's staunchest allies, suffered a humiliating election defeat Saturday at the hands of an opposition leader who has vowed to pull troops out of Iraq.

Labor leader Kevin Rudd, a Chinese-speaking former diplomat, has also promised to sign the Kyoto Protocol on global warming, leaving the U.S. as the only industrialized country not to have joined it.

Howard, who reshaped his country's image abroad with unwavering support for the war in Iraq, dominated Australian politics for more than a decade but failed to read the signs that voters had grown tired of his rule.

Adding to the sting of his party's decisive defeat, official results showed Howard was likely to lose his parliamentary seat altogether. Only one other sitting prime minister has lost his district in the 106-year history of Australia's federal government.

The six-week campaign was fought largely over domestic issues such as economic management and Howard's unpopular labor law reforms that critics say strip workers of their rights.

But a strong underlying factor was the prospect of a generational change.

Rudd, who was expected to be sworn in as prime minister in the coming week, had accused Howard of being out of touch with modern Australia and ill-prepared to deal with issues such as climate change and high-speed Internet.

Howard campaigned on his economic management, arguing that his government was mostly responsible for 17 years of unbroken economic growth, fueled by Chinese and Indian demand for Australian coal and other minerals. He contended that Rudd could not be trusted to maintain prosperous times.

Rudd promised to pull Australia's 550 combat troops from Iraq in a phased withdrawal and to quickly sign Kyoto. Howard had rejected withdrawal plans for Australia's troops in Iraq and refused to ratify the pact on reducing greenhouse gas emissions.

"Today the Australian people have decided that we as a nation will move forward," Rudd said in a victory speech before hundreds of cheering supporters in his home state of Queensland. "To plan for the future, to prepare for the future, to embrace the future and together as Australians to unite and write a new page in our nation's history."

Australia is the latest country to see elections turn out governments that contributed to the U.S. war in Iraq.

Poland's new prime minister, Donald Tusk, has vowed to take a firmer stand in relations with the United States. He said in his inaugural address Friday that by the end of next year Poland would withdraw its 900 troops from Iraq, where it leads an international contingent of about 2,000 soldiers from 10 nations in the south-central part of the country.

Howard had stayed on to fight for a fifth term in office despite months of negative opinion poll numbers and appeals from some colleagues to quit. He took the blame for his government's defeat.

"I accept full responsibility for the Liberal Party campaign, and I therefore accept full responsibility for the coalition's defeat in this election campaign," Howard said in his concession speech in Sydney.

He said it appeared "very likely" he would lose his seat in parliament to former television journalist Maxine McKew.

Rudd's Labor Party had more than 53 percent of the vote with over 75 percent of ballots counted, compared to 46.8 percent for Howard's coalition, according to the Australian Electoral Commission.

An Australian Broadcasting Corp. analysis showed that Labor would get at least 81 places in the 150-seat lower house of Parliament — a clear majority.

Few in Rudd's team have any federal government experience. They include a former rock star — one-time Midnight Oil singer Peter Garrett — and a number of former union officials.

Rudd has more experience in foreign policy than any other area of government and was expected to adopt a nuanced, non-confrontational approach to diplomacy. He sent "greetings ... to our great friend and ally the United States" in his victory speech.

The Bush administration congratulated Rudd.

"The United States and Australia have long been strong partners and allies, and the president looks forward to working with this new government to continue our historic relationship," said White House spokeswoman Emily Lawrimore.

The White House also applauded Howard's time in office.

"Mr. Howard served the people of Australia well by pursuing policies that led to strong economic growth and a commitment to keeping Australians safe by fighting extremists and their ideology around the world."

Rudd's election as Labor leader 11 months ago marked the start of Howard's decline in opinion polls.

Howard held his district for 33 years, and his four straight national election victories made him one of Australia's most successful politicians.

Despite Rudd's stances on Iraq and climate change, little else was expected to change in Australia's trade and economic policies.

Rudd has pledged to govern as an "economic conservative," while pouring money into schools and universities. He will curtail sweeping industrial reform laws that were perceived to hand bosses too much power.