Prime Minister John Howard on Sunday called general elections for Nov. 24 that will decide who will shepherd Australia's economic boom and whether the country will start pulling troops out of Iraq.

Howard, who has been prime minister for the last 11 years, faces a tough battle to win a fifth term against Labor Party opposition leader Kevin Rudd, a Chinese-speaking former diplomat who for months has held a commanding lead over the conservative Howard in opinion polls.

Howard's announcement marks the start of the official run-up to the elections, though both sides have been campaigning unofficially for weeks.

Howard on Sunday sought to place the guardianship of an economic boom spanning more than 15 years as the key campaign issue. The country's coal and mineral-driven economy continues to boom thanks to voracious demand from China, India and elsewhere.

"People must decide in the weeks ahead who is better able to not only to preserve the prosperity that we now have, but also to build it further and to make sure that it is fairly shared throughout the Australian community," Howard said. "Love me or loathe me, the Australian people know where I stand on all the major issues of importance to their future."

Rudd responded by saying Australia needed new leadership to capitalize on the economic boom, and accused Howard of being unable to deal with new-age issues such as global warming.

"Our country has a future too full of promise to allow a government that's been in office for 11 years, a government that's lost touch, and a government that's gone stale, just to continue on," Rudd said.

Australia's deployment of 550 combat troops in the U.S.-led coalition in Iraq is a background issue, but an important one because it is an area of clear difference and affects Australia's most important foreign relationship — with the United States.

Howard, a staunch ally of President Bush, sent 2,000 troops to support U.S. and British forces in the 2003 Iraq invasion and says the 1,600 Australian forces still involved in the operation will stay as long as they are needed.

Rudd argues that the Iraq war has made Australia more vulnerable to terrorist attack and has promised to withdraw Australia's 550 combat troops, in consultation with Washington, while leaving the rest there in lesser roles.

Howard on Sunday conceded his Iraq policy was unpopular with many Australians, but said, "If America is defeated in Iraq, then that would be bad for the Middle East, it would be an enormous boost to terrorism, that would be particularly bad for us in our own region."

Rudd used the Iraq deployment and other issues to try to turn Howard's claim to greater experience against the prime minister.

"Mr. Howard has had a lot of experience into taking Australia into a war without an exit strategy," Rudd said. "Mr. Howard has a lot of experience in denying that climate change represented an economic and environmental challenge for this nation's future."

Rudd has promised a Labor government would sign up to the Kyoto Protocol on reducing greenhouse gas emissions, something Howard has refused to do, making Australia and the U.S. the only industrialized nations to reject the U.N.'s mandatory carbon emission reduction targets.

The leaders' personalities are also key.

Both Howard and Rudd are bookish, with middle-class backgrounds and long records of public service that each hopes will inspire trust and an image of steadfastness among voters.

Rudd, 50, has campaigned hard in recent months to project an image as a new-generation leader, a Web surfer with a MySpace page who understands the challenge of climate change.

Howard, who at 68 is Australia's second longest-serving leader, has claimed credit for the unprecedented 15-year economic surge. He is a reformed global warming skeptic who argues against Kyoto-style mandatory emission targets and favors a more flexible international agreement to encourage all nations to reduce carbon pollution.

His mantra to voters has become: changing government means risking prosperity.

Win or lose, it will be Howard's last election. Under pressure from within his own party, Howard has promised to retire during the next term if he is re-elected, with longtime Treasurer Peter Costello his nominated successor.