WASHINGTON — Eight months into his presidency, Barack Obama has become a global celebrity, far more popular abroad than he is at home and sometimes eclipsing foreign leaders among their own people.

He has sought to use that renown to repair America's image in the world, extending an "open hand" in major speeches in more than a dozen countries. Obama has restarted talks to limit nuclear weapons, begun engaging adversaries, helped orchestrate the world's response to economic collapse and reversed Bush-era policies that had angered allies and distanced the United States from the world community.

But just as his domestic honeymoon has clearly ended, international events have demonstrated the limits of Obama's personal charm.

As he takes the stage to address the United Nations for the first time Wednesday, Obama will face world leaders — adversaries and allies alike — whose rebukes of the new American president serve as reminders that the world's differences with the United States transcend who is in the White House.

European nations have refused to send significant numbers of new troops to aid the U.S.-led war effort in Afghanistan. Few countries have agreed to accept detainees from the U.S. military prison at Guantanamo Bay, Cuba. Scottish officials ignored Obama's plea to keep the Lockerbie bomber in prison, and U.S. efforts to head off a coup in Honduras were ineffective. North Korea continues to develop nuclear weapons, Iran may be doing so, and Middle East leaders have rebuffed Obama's efforts at peacemaking.

"When he came into office, there was kind of a sigh of relief around the world because he wasn't Bush," said Leslie Gelb, a former president of the Council on Foreign Relations. "What was he going to do to solve these problems? They haven't seen that yet."

Obama's top foreign policy advisers say the president's popularity abroad has helped clear a path for substantial policy achievement by helping improve respect for the United States in other countries.

Susan Rice, the U.S. ambassador to the United Nations, said in an interview that the administration's conscious decision to break with the past — and specifically with the presidency of George W. Bush — has altered the dynamics of world politics.

"It's palpable every day with a new openness and a new willingness to listen and respect our positions and our policies, a readiness to cooperate even where in the past we have met resistance," she said.

"Not just change in tone and reaction, but change in policy that has been noted and recognized."

HIGH HOPES

Yet even staunch Obama defenders such as Rice concede that the expectations for the president abroad were exceedingly high.

"What did you expect?" she said. "The president gets elected and all of a sudden, you know, we reach nirvana in short order? I mean, that's a little bit ridiculous."

Obama, who arrives in New York City tomorrow for the annual U.N. gathering, began building expectations for peace in the Middle East in the first months of his presidency and raised hopes even higher with a June speech in Cairo in which he pledged that he could make things happen.

He asked Israel to ease its embargo of the Gaza Strip and freeze construction in West Bank settlements. He asked the Arab states to take steps toward "normalization" of ties with Israel. He made restarting Israeli-Palestinian peace talks a priority, announced plans to repair relations with Syria and said he will engage, rather than confront, Iran.

Yesterday, the White House announced that Obama plans to hold a three-way meeting with Israeli Prime Minister Benjamin Netanyahu and Palestinian Authority President Mahmoud Abbas in New York on Tuesday.

It will be the first meeting between the latter two since Netanyahu took office.

"It is another sign of the president's deep commitment to comprehensive peace that he wants to personally engage at this juncture," said special envoy George Mitchell.

MIDEAST FAILURES

But progress has been slow, and the frustration has built on all sides — among Israeli officials upset that he focused public demands on them; among Arabs, especially Palestinians, over his inability to wrest concessions from Israel; among human rights activists who say his idealism has not been borne out in action.

"I think there has been too little appreciation of realities and too much well-intentioned belief in the power of rhetoric and good will," said Mark Heller, principal research associate at the Institute for National Security Studies at Tel Aviv University.

Rice countered that Obama has made "significant progress on a wide array of issues" relating to the Middle East peace process, which she noted has been a difficult problem for "every prior administration."

But White House officials said they do not expect an agreement on settlements to be announced at the three-way meeting this week.

The Islamist Hamas movement in the Gaza Strip has said that Mitchell's inability to negotiate that agreement with Israel proves Obama's shortcomings.

It is "proof of the failure of the Obama administration in helping the Palestinian people," Hamas spokesman Fawzi Barhoum said in a statement, reflecting a broad skepticism among Arabs about whether Obama's overture to the Muslim world would make a difference on the ground.

Israeli officials, meanwhile, have also expressed concern that his policy of engagement toward Iran is allowing too much time to pass without any steps to slow Tehran's nuclear program.

Israel and other nations say they suspect that Iran is intent on building a weapon; Iran says its program is peaceful.

The United States has agreed to hold discussions with Iran and several other countries on Oct. 1, prompting concerns in Israel and among critics of the administration that delay will inevitably result.

"It is not just here that the administration is starting to be mugged by reality," Heller said. "They used nice words and tried to engage. ... In the meantime, the scorecard on North Korea is not much better. On (Venezuelan President Hugo) Chavez it is not much better. We don't see reforms pushed in Cuba."

ONLY HUMAN

Obama's political struggles at home and his performance internationally have led some observers abroad to remark that a charismatic leader who seemed to be walking on water last year is only human, subject to the same bruising political battles as everybody else.

Several have noted that his effort to cultivate better relations with Russia has not produced concrete help from Moscow in dealing with Iran and that — so far — Israel has stiff-armed his plea for an end to Jewish settlements.

Obama has made good on his promises to begin winding down the Iraq war and to take steps to close Guantanamo.

But at the same time, he has ramped up U.S. fighting in Afghanistan, a sore point with many Europeans and a difficult political issue for Obama's counterparts around the world.

U.S. officials point to their success in getting Russia and China to back stiff sanctions on North Korea as evidence of their success on the world stage.

The real test of attitudes in European capitals is likely to emerge in coming months, experts there say, particularly if Obama fails to make headway on his main foreign policy objectives or if the war in Afghanistan causes an unacceptable casualty rate among European soldiers attached to NATO's International Security Assistance Force.

In his speech to the General Assembly on Wednesday, Obama will lay out "his view of international cooperation in the 21st century and the need to move beyond old divisions," Rice said.

Rice's predecessor, John Bolton, predicted that "the greeting will be rapturous" for the new U.S. president.

"It's a triumph for Obama personally, but I have yet to see his personal popularity translate into concrete steps forward," Bolton said.