A draft Security Council resolution that condemns Israeli settlement building on Palestinian land is expected to push the US president, Barack Obama, into the uncomfortable position of using his first veto in the top UN chamber.
The Palestinians have returned to the UN's 15-nation body to settle grievances with Israel after US-brokered talks between the two sides broke down last year, saying that Washington will lose credibility if it blocks their draft resolution.
But the White House is sticking to a long-held position that peace should come directly from the two sides - not in New York - and is widely expected to be the only country voting against the document when balloting takes place.
Mr Obama has repeatedly said Israeli settlements are "illegitimate" and has been less supportive of the Jewish state than some of his predecessors. Analysts and diplomats describe this as an awkward position for the US president.
A diplomat from the UN Security Council said: "If the resolution is put to vote, the Americans, by virtue of the compulsion of their domestic politics, and in their domestic politics all these resolutions are viewed as being anti-Israeli would be left with not much choice but to veto."
The diplomat said the Security Council will probably vote on the resolution after the Quartet of Middle East peacemakers - the US, the UN, the European Union and Russia - meet in Munich on February 5.
Direct talks between the two sides broke down over the settlements issue last year, after the end of an Israeli building moratorium on September 26. Construction has since begun on as many as 2,000 units in the West Bank, the UN says.
The draft document reiterates calls for Israel to halt building on Palestinian soil. Settlements built in occupied territory since 1967, including disputed East Jerusalem, are "illegal and constitute a major obstacle to the achievement of a just, lasting and comprehensive peace", it says.
The document is sponsored by Lebanon, which holds the Arab seat on the council, and more than 120 co-sponsors. It has support from all 14 council members except the US, one of the body's five permanent, veto-wielding members.
"There is nothing in the text which anyone disagrees with," the diplomat said.
Hillary Clinton, the US secretary of state, has said that "New York is not the place to resolve the long-standing conflict". Mark Regev, the Israeli government spokesman, said the dispute "should be resolved in direct negotiations".
The Palestinians say a UN resolution will revive dialogue by forcing Israel to suspend settlement construction, which they have made a precondition for more talks. The Palestinian negotiator, Nabil Shaath, said they will push ahead "whether or not the United States wants it".
"If you use the veto against this resolution, you will forever lose what's left of your credibility as a sponsor of the peace process," Mr Shaath said in a warning to Washington.
The White House is also under pressure at home. A group of prominent Americans, including former State Department officials Thomas Pickering and James Dobbins, wrote a letter urging the US president to adhere to the rules of international law.
"If the proposed resolution is consistent with existing and established US policies, then deploying a veto would severely undermine US credibility and interests, placing us firmly outside of the international consensus, and further diminishing our ability to mediate this conflict," it said.
The liberal pro-Israel lobby group J-Street urged Mr Obama to avoid a veto, saying the administration should "work to craft language, particularly around Jerusalem, that it can support condemning settlement activity and promoting a two-state solution".
But many commentators insist the UN resolution will not advance peace between Palestinians and Israelis, and warned Mr Obama against a big policy shift in the wake of November's mid-term elections, when voters swung to the Republican right.
Alan Dershowitz, a Harvard law professor, called the draft "utterly unrealistic" in The Wall Street Journal. He said it was also a "stalking horse for the Palestinian effort to secure a further UN resolution unilaterally declaring Palestinian statehood".
Some analysts question whether the Palestinians are using the draft as a bargaining chip to win concessions from the US. Others say the Palestinian Authority will push ahead to regain the credibility it lost through the release of the so-called Palestine Papers.
The leaked documents have embarrassed Palestinian officials by revealing that they offered Israel big concessions on sensitive issues, such as the fate of Jerusalem and Palestinian refugees, during previous rounds of peace talks.
"If the Palestinians are trying to corner the Obama administration and force concessions or force them not to veto - I don't think they'll be successful," said Mike Singh, an analyst for The Washington Institute for Near East Policy.
"The administration is clear that the resolution is not helpful and they're prepared to veto. This doesn't reflect the administration's policy on settlements, about which they've been clear. It reflects a view on what's constructive to the peace process."
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