WASHINGTON - The unrelenting global troubles confronting Barack Obama are about to converge on him all at once.
In four days, Obama will plunge into the politics of the United Nations and host a summit in Pittsburgh on the world's wobbling economy. The international stage is coming to him, and no one standing on it with him will have higher stakes.
Obama is under pressure to push along stalled Mideast peace, prove the United States is serious about climate change and rally allies against the nuclear threats of Iran and North Korea. Restless leaders in Europe and elsewhere are pressing Obama to reform risky U.S. financial behavior and get Congress on board.
He also bears the load of two inherited wars that now have his imprint - the one he's winding down in Iraq and the one that's widening in Afghanistan. Eight years after the Sept. 11 attacks, Obama must hold together international will as he tries to keep Afghanistan from becoming an al-Qaida launching pad again.
He will have his chances.
His first speech to the 192-member General Assembly will outline his view of leadership, emphasizing a new brand of cooperation as if to underline he is not Bush. As U.N. ambassador Susan Rice described the message: "Everybody has a responsibility. The U.S. is leading anew. And we are looking to others to join."
Obama will be the first U.S. president to be chairman of the Security Council, whose rotating presidency is in U.S. hands this month during the annual meeting of the General Assembly. He expects to emerge from that special summit on arms control with a resolution that advances his goals of a world free of nuclear weapons.
The measure will try to put heat on Iran and North Korea without singling out any country.
Obama is under pressure from world leaders to put more muscle into fighting climate change. He will seek to do that this week, too, with a speech at a U.N. climate conference.
Time is short for the United States to have leverage. An international conference is set for December in Denmark to reach a new global climate pact. Although the House has passed a bill to limit greenhouse gases, Senate action may fade until next year.
Obama, who arrives in New York on Monday for the annual U.N. gathering, will meet privately with the leaders of Russia, China and Japan. Less formal sessions will take place all week.
When the focus shifts to Pittsburgh, Obama will run the Group of 20 summit of the rich and developing countries that represent 80 percent of world economic output. Although their united, expensive efforts this year helped halt the economic slowdown, there is enormous work left and wide divisions about how to proceed.
"All of us need to act more responsibly on behalf of a better economic future," Obama said in Saturday's radio address.