IT was supposed to be the week President Barack Obama saved the world. More than 100 heads of state are preparing to descend on New York for talks on halting climate change, promoting nuclear disarmament, defeating terrorism in Pakistan and tackling poverty in sub-Saharan Africa — all before a G20 meeting in Pittsburgh on Friday aimed at reaching agreements on global financial regulation and curbing bankers’ bonuses.

The headline-grabber was expected to be the relaunch of the stalled Middle East peace process, to be followed a week later by America’s first direct talks with Iran since the Islamic revolution in 1979.

Instead, attempts to revive talks between Israelis and Palestinians, the cornerstone of the administration’s foreign policy, have failed so far. Western diplomats say it will take all the president’s considerable charisma to revive them.

A three-way meeting between Obama and the Israeli and Palestinian leaders was planned for Wednesday during the United Nations general assembly’s annual opening session in New York. Officials even talked of setting a two-year deadline for the establishment of a viable Palestinian state.

Obama’s special envoy, George Mitchell, returned empty-handed yesterday after a week of shuttling between Binyamin Netanyahu, the Israeli prime minister, and Mahmoud Abbas, the Palestinian National Authority president.

Last night it was announced that a tri-lateral meeting of the parties would be held on Tuesday.

“They say the darkest hour is right before the dawn, and we’re in the darkest hour,” said Martin Indyk, director of foreign policy at the Brookings Institution, a leading Washington think tank, and former US ambassador to Israel.

The main sticking points are over a proposed freeze on Israeli settlement-building in the West Bank and any reciprocal steps by Arab states such as overflight rights, trade negotiations and tourist visas for Israelis.

Mitchell had pushed for a one-year moratorium on all Israel’s settlement activity in the West Bank and eastern

Jerusalem. To his exasperation Netanyahu started building again in the West Bank. The Israeli leader offered only a slowdown in construction.

Abbas told Mitchell he would not resume talks unless building was halted, according to the Palestinian negotiator Saeb Erekat. The only hope now is that Obama himself will be able to salvage the situation in separate meetings with the two men this week.

“President Obama and I are very patient and very determined,” said Hillary Clinton, the secretary of state. “We know this is not an easy road for anyone to travel.”