All three pathways are fraught with potential pitfalls and hinge on cooperation from often unreliable nations. Obama also risks being branded as naive and misguided if the efforts fail, particularly in Syria, where he's used the prospect of diplomacy to put off a military strike in retaliation for a chemical weapons attack.
Still, the recent developments mark a significant shift on a trio of issues that have long proved problematic for Obama at the United Nations. His former Iranian counterpart used the annual U.N. General Assembly meetings as a venue for fiery, anti-American speeches. Failed Middle East peace talks led the Palestinians to seek statehood recognition at the U.N. despite staunch American objections. And the Obama administration has been stymied on Syria at the U.N. Security Council due to intractable Russian opposition.
But this year, Iran has a new leader who is making friendly overtures toward Obama, raising the prospect of a meeting at the United Nations. U.S.-brokered peace talks between the Israelis and Palestinians have resumed - though on an uncertain course. And Russia has joined with the U.S. on a diplomatic deal to strip Syria of its chemical weapons.
Joel Rubin, a former State Department official who now works at the nonproliferation organization Ploughshares, said the confluence of events underscores an often frustrating aspect of diplomacy.
"You never know when it's going to break," said Rubin. He said Obama's biggest test now is to recognize if opportunities morph into stalling tactics.
Obama's advisers cast the sudden signs of progress as an outgrowth of the president's long-standing preference for resolving disputes through diplomacy and, in the case of Iran and Syria, with pressure built up through economic sanctions and the threat of military action.
"He said we'd be open to diplomacy, we'd pursue engagement, but that there would be pressure if Iran failed to take that opportunity," said Ben Rhodes, Obama's deputy national security adviser. And on Syria, Rhodes said it was the credible threat of a U.S. military strike "that opened the door for this diplomacy."
Obama was due to arrive in New York Monday afternoon. He will address the U.N. on Tuesday, a speech aides say will touch on developments in Iran, Syria and Middle East peace. The issues will also be at the forefront of some of the president's bilateral meetings with world leaders, including a sit-down with Palestinian Authority President Mahmoud Abbas and Lebanese President Michel Suleiman, whose country is burdened by the flow of refugees from neighboring Syria.
But Obama's most closely watched meeting may end up being with Iranian President Hasan Rouhani. No encounter is scheduled, but U.S. officials have left open the possibility the two men might talk on the sidelines of the international gathering.
If they do, it would mark the first meeting of U.S. and Iranian leaders in more than 30 years. A meeting could also be a precursor to renewed talks on Tehran's disputed nuclear program - though bridging differences over Iran's right to enrich uranium and maintain those stockpiles will be a far tougher task than arranging a handshake.
The election of Rouhani, a moderate cleric, signaled frustration among many Iranians with their country's international isolation and the crippling impact of Western sanctions. Obama and Rouhani have already exchanged letters. And the new Iranian president's rhetoric has so far been more palatable to the U.S. than former leader Mahmoud Ahmadinejad, who would threaten Israel as well as lambast the U.S. in his annual remarks at the U.N.
Trita Parsi, the president of the National Iranian American Council, said Rouhani shares with Obama a need to prove to a domestic audience that diplomacy can produce concrete results.
"If he can't show that his diplomatic approach will pay more dividends for Iran that Ahmadinejad's theatrics, then it's back to the conservatives being in the driver's seat. And the flexibility that Rouhani currently has will be lost," Parsi said.
As Rouhani considers re-engaging with the U.S., he's closely watching diplomatic developments in Syria, an Iranian ally.
A chemical weapons attack near Damascus in August brought the U.S. to the brink of a military strike. But an idea floated by Secretary of State John Kerry turned into a last-minute overture from Russia - another backer of Syrian President Bashar Assad - and resulted in a deal to turn Syria's chemical weapons stockpiles over to the international community.
The breakthrough was particularly unexpected given that Russia has thwarted U.S. efforts to punish Assad through the U.N. Security Council. When Obama was on the verge of launching a strike against Assad's regime, he said the U.N. had an "incapacity" to address Syria's violation of international agreements banning the deployment of deadly gases.
Now the U.S. once again sees a role for the Security Council. The U.S. wants the panel to approve a resolution making the U.S.-Russian agreement legally binding in a way that is verifiable and enforceable. But a key obstacle remains, given U.S. and Russian disagreement over whether to put the resolution under Chapter 7 of the U.N. Charter.
Chapter 7 deals with threats to international peace and security and has provisions for enforcement by military or nonmilitary means, such as sanctions. Russia is sure to veto a resolution that includes a mandate for military action.
The prospect of diplomacy in Iran and Syria has overshadowed tenuous progress in recent months in restarting direct talks between the Israelis and Palestinians. Talks resumed this summer after months of prodding by Kerry, but the prospect of a resolution on issues that have long had the Israelis and Palestinians at odds remain as slim as ever.
Palestinian leaders, frustrated by the stalemate, have taken their case in recent years to the United Nations, where there is broad support for their bid for statehood. While the U.S. supports Palestinian statehood, it says that status can only be achieved through direct negotiations with the Israelis.
That's put Obama in the awkward position of arguing against Palestinian efforts during his previous trips to the U.N. American opposition stymied Palestinian efforts to become full U.N. members in 2011, but the Palestinians succeeded in a bid to gain implicit statehood recognition last year.
The 2012 measure passed overwhelmingly, with the U.S. and just a handful of other nations voting no.