WASHINGTON—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.

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.

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 today 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.

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.