The US efforts to secure a deal with Egypt and other Arab countries reflect Washington's concern to win their backing for sanctions against Iran over its nuclear program by offering a concession over US ally Israel, even though Washington says such a ban is impossible without peace in the Middle East.
Western diplomats say that the success or failure of a month-long meeting on the 1970 nuclear Non-Proliferation Treaty (NPT) currently under way in New York hinges on the sensitive negotiations on an Egyptian proposal to hold a conference on establishing a zone free of nuclear arms in the Middle East.
"If we can't get a deal on the Middle East in the next few days, the NPT review conference will probably collapse," a Western diplomat told Reuters. "It's what happened in 2005."
Another Western diplomat familiar with the talks was guardedly optimistic. Despite the appearance of a chasm separating the Arabs from the United States and the four other permanent UN Security Council members, "informal conversations indicate the sides are not in reality too far apart," he said.
"The next few days will be critical," the envoy added.
NPT review conferences are held every five years to take stock of and assess compliance with the anti-nuclear arms pact. They make decisions by consensus, which makes it difficult to reach agreements, since all 189 NPT signatories have a veto.
The last review conference in 2005 was widely viewed as a failure. It collapsed due to Egypt's outrage at the failure to move forward on the Middle East nuclear-arms-free zone idea and developing nations' anger at the United States for refusing to reaffirm disarmament pledges from 2000.
Both Egypt and the US are eager to avoid another collapse. Cairo does not want to be labeled as a spoiler again, while the United States wants an outcome that helps ratchet up the pressure on Iran and supports President Barack Obama's determination to move toward a world free of nuclear arms.
If there is no deal on the Middle East, envoys say, there can be no agreement on a final declaration that "names and shames" Iran and North Korea and acknowledges the disarmament steps the big powers have taken, which Washington and its allies want.
The United States and the four other countries allowed to keep nuclear arms under the NPT - fellow Security Council veto powers Britain, France, China and Russia -- have been negotiating with the Arabs on the sidelines of the NPT meeting, which concludes at the end of next week, to secure a deal.
Egypt, which chairs the powerful 118-nation bloc of non-aligned developing nations, circulated a proposal to all 189 NPT signatories calling for a conference by next year on ridding the Middle East of nuclear arms in which all countries in the region would participate.
Washington came up with a counterproposal, which calls for "the convening of a conference in 2012-2013 of all states of the Middle East to discuss implementation of the 1995 resolution in its entirety."
The 1995 resolution adopted by NPT signatories calls for making the Middle East a zone without atomic bombs or other weapons of mass destruction, and notes that the Middle East peace process could help to make it a reality.
Israel neither confirms nor denies having nuclear arms.
Egypt has insisted that both Israel and Iran would have to participate in such a conference, even though Tehran does not recognize Israel's right to exist. Western diplomats agree, but say that Israel would be reluctant to participate.
Still, the Jewish state could be persuaded, they say.
"Israel will attend if the cost of not attending is higher than the cost of attending," a senior Western diplomat said.
Among the possible enticements for Israel would be to ensure that any such regional conference also covers biological and chemical weapons, not just nuclear arms, as well as regional security and other issues, Western diplomats said.
Like nuclear-armed India and Pakistan, Israel never signed the NPT and is not officially at the NPT review conference. Egypt and Syria are outside the chemical weapons convention that bans production, stockpiling and use of chemical arms.
Diplomats say the sticking points include the format for such a conference and the question of whether it should be organized by the United Nations, as the Arabs would like.