Reuters PhotosPresident Obama greets Secretary General Ban Ki-moon at the United Nations on September 22, 2009.

The sixty-fourth United Nations General Assembly session, which shifts into high gear this week, could be memorable not so much for what is said in mostly predictable speeches by a long lineup of world leaders as for the sustained involvement and presence at UN headquarters of one of them: Barack Obama.

The American president plans to be present for more of the General Assembly session than any of his predecessors (if you don’t count George H.W. Bush’s stint as American ambassador in the 1970s). In another first for the White House, he will chair a meeting of the Security Council on Thursday. On Tuesday he will attend a daylong summit on climate change arranged by Secretary-General Ban Ki-moon. And yes, on Wednesday he will deliver the speech that is expected to restore a cooperative American global vision. Over several days he will meet on the sidelines with other leaders. And all that is before heading to Pittsburgh for the G-20 meeting of leading economic powers.

He may easily upstage the theatrical Muammar el-Qaddafi of Libya, who plans to make his first visit to the UN and the United States, in part because a Libyan diplomat, Ali Treki, has just become president of the General Assembly for 2009-10, succeeding Miguel d’Escoto Brockmann of Nicaragua.

Diplomats around the UN may wonder why it took so long for the US president to make even a quick a trip to the UN, given that he has had time for extensive foreign travel despite his domestic woes. But his UN ambassador, Susan Rice, has been laying groundwork for sustained engagement for months, stating publicly that the organization is essential to solving global problems.

On Friday Secretary of State Hillary Clinton spoke at the Brookings Institution about an extensive American agenda for the General Assembly. She, too, will chair a Security Council session, on violence against women in war and peacekeeping. Strong US support for international development work and the advancement of women is anticipated and welcomed by UN officials working in development and many member countries.

Obama’s high-profile UN appearances carry some risks. The American right could find another cause for ill-informed hysteria–the UN has long loomed as the “black-helicopter threat” that would seize our national parks (that’s Unesco’s World Heritage and Biosphere Reserve programs) and, indeed, our national sovereignty. It rankles conservatives that the UN is an organization of 191 other national interests apart from our own, and it operates beyond the control of Congress. The UN is full of foreigners, as Madeleine Albright liked to say when she was the American envoy, and there was nothing she could do about it.

On foreign shores, Obama will be watched for signs of a new kind of American bullying. Some developing nations have already attacked the climate summit as an unauthorized negotiating session that will pre-empt open debate in Copenhagen in December. In the eyes of many poor countries in Asia and Africa, the industrial nations of Europe and North America should not force poorer countries to make binding commitments on emissions, certainly not unless they are compensated. The United States has long wanted everyone to be part of the solution, especially China and India, which rank among the top four largest polluters in absolute terms. India has been most vocal in insisting that it cannot compromise on continued industrial growth, much of which is fueled by coal. Brazil, a rising economic power, has objected to outside demands that would limit deforestation of rainforest land and other natural resources.

Unease will also greet Thursday’s Security Council debate on stopping the spread of nuclear weapons. Rose Gottemoeller, the Obama administration’s assistant secretary of state for verification, compliance and implementation, made it clear months ago that India, Pakistan and Israel–all with bombs–should sign the 1968 Nuclear Nonproliferation Treaty and, ultimately, the Comprehensive Test Ban Treaty, which the United States has yet to ratify. Iran, which signed the NPT, is being told to adhere to it. North Korea is still a moving target as it develops weapons and delivery systems while moving in and out of inspection range. None of those countries wants to be on the Security Council’s agenda. These are sharp reversals of Bush-era policy.

A year ago, a Gallup poll found that around the world Obama enjoyed a broad lead as candidate for president (though in some polls, India and China favored John McCain). His ratings may have slipped abroad as well as at home lately, but anecdotal evidence from international media suggests he continues to enjoy foreign popularity and support, if only out of lingering fascination. Whether the government leaders now on the receiving end of Obama’s global prescriptions share that positive opinion will be tested this week.