The problems do not get any easier as President Bush attends his final summit with leaders of industrialized democracies.

Disputes over global warming, worries about soaring oil prices and uncertainty about Iran and North Korea's nuclear ambitions pose daunting challenges for Bush when he sits down with presidents and prime ministers Monday.

There are fewer than 200 days left in his term, and Bush's dwindling presidency is a major factor hanging over the meetings involving leaders from Japan, Germany, Britain, France, Italy and Canada at a Group of Eight summit in Toyako, on the northern Japanese island of Hokkaido.

With Bush en route to Japan on a nonstop flight Saturday, there is a mix of high challenges and low expectations for the summit.

Atop the agenda is reaching a deal that would set targets for reducing the pollution that causes global warming. But few expect major headway or concessions from Bush. He insists on holding China and India, fast-growing economies and among the world's biggest polluters, to the same emission-reduction standards as older, developed economies.

Japan's prime Minister, Yasuo Fukuda, would like to emerge with an agreement on 50 percent overall reductions in greenhouse gases by 2050.

Some European countries and developing nations favor establishing targets for cutting emissions by 2020. Scientists say those targets are needed to avoid the worst effects of global warming.

Bush planned a pre-summit meeting and news conference on Sunday with Fukuda. On the sidelines of the G-8 meeting, Bush also scheduled separate meetings over the next few days with the leaders of Germany, China, South Korea, Russia and India.

Michael A. Levy, director of energy security and climate change at the Council on Foreign Relations, a New York-based think tank, said he did not expect breakthroughs on global warming, in part because other G-8 members realize that Bush's days in office were dwindling.

The Japanese, who are driving the agenda and favor strong emission-reduction targets, "acutely understand there is going to be a different American approach to climate change in a year," Levy said.

Both Democrat Barack Obama and Republican John McCain have argued for stronger standards for reducing greenhouse gas emissions than those advocated by Bush.

"We'll have a new U.S. president in office. The expectation is that either McCain or Obama would be a little bit more forward-leaning and we could make some more headway," said Julianne Smith, director of the Europe program at the Center for Strategic and International Studies.

The United Nations began negotiations late last year on a climate change pact to take over when the first phase of the Kyoto Protocol — which the United States has not ratified — expires at the end of 2012. Negotiators face a deadline of December 2009, when some 190 nations will meet in Denmark.

Bush said he supports efforts to agree on setting short-term and long-term goals. But he also said countries such as China and India — not subject to the same cuts that apply to more developed industrial economies — need to be included. "It's tough to get consensus," Bush said.

Bush has urged a halt in the growth of carbon dioxide and other greenhouse gases by 2025, but has not offered a strategy for pollution reductions or backed mandatory emission cuts. He has supported an increase in auto fuel economy, a requirement for a huge increase in use of ethanol and other biofuels, and for developing clean energy technologies.

Bush himself says a priority of this year's summit is not advancing new initiatives but making good on ones from previous summits, especially promises for health aid for countries in Africa and other underdeveloped nations.

"We need to show the world that the G-8 can be accountable for its promises and deliver results," Bush said ahead of the summit. "America is on track to meet our commitments. And in Japan, I'll urge other leaders to fulfill their commitments, as well."

More than 1,000 people marched in northern Japan on Saturday to protest the summit. Police arrested four protesters after a brief scuffle. Demonstrators at a park in central Sapporo demanded that the summit nations take urgent measures to stop global warming, grant indigenous people greater rights, combat world poverty and battle discrimination.

Bush's trip comes amid fresh questions on the makeup of the Group of Eight and its relevance to today's global economy. When the gathering was first set up in the 1970s it consisted of five nations that were the world's undisputed economic powerhouses, all democracies: the U.S., Britain, Japan, France and Germany.

The annual meetings were expected to focus on global economic issues. Canada, Italy and Russia were added later, bringing the membership to eight.

China, the world's third largest economy — after the U.S. and Japan — is not a member. Neither is India, the world's most populous democracy and fourth-largest economy, according to a World Bank update issued last week that ranks countries according to their gross domestic product in terms of purchasing power.

Brazil, a nonmember, has a bigger economy than that of G-8 members Italy and Canada, according to the World Bank report. The economies of Spain, Mexico and South Korea are bigger than that of G-8 laggard Canada.

Bush has pushed for a wider role for these growing economies that are not G-8 members, and they were invited to join with the core group on Wednesday for a "major economies meeting."

The U.S. was expected to push for political statements on government suppression in Myanmar; the increasing violence in Afghanistan from Taliban insurgents; the Middle East peace process; terrorism; and developments on nuclear programs in North Korea and Iran, including North Korea's recent destruction of a nuclear facility that had produced plutonium.

Surging global oil prices and slumping economies in most of the G-8 countries were also were expected to be discussed, although options for action seemed to be limited.