The United Nations General Assembly was set to vote on condemning Israel for Palestinian deaths in Gaza in a resolution fiercely opposed by the United States, which wants Hamas to face condemnation.
US Ambassador Nikki Haley slammed the Arab-backed measure as "fundamentally imbalanced" for its failure to mention Hamas and has proposed an amendment that condemns the Palestinian militant group.
"Any resolution focused on the protection of civilians in Gaza must recognize the destabilizing and reckless actions of Hamas, which endanger the lives and livelihoods of innocent civilians," Haley wrote in a letter sent to fellow ambassadors on the eve of the vote.
At least 129 Palestinians have been killed by Israeli fire during protests near the border with Gaza that began at the end of March.
The Arab-drafted text condemns Israel's use of "excessive, disproportionate and indiscriminate force" against Palestinian civilians and calls for protection measures for Palestinians in Gaza and the occupied West Bank.
The 193-nation assembly will vote first on the US-drafted amendment condemning Hamas for "inciting violence" along the border with Gaza before the vote on the resolution.
Diplomats expect the US amendment to fail and the Arab-backed resolution to be adopted, but it remains unclear how many votes it will garner in the face of strong US opposition.
Arab countries backing the measure turned to the General Assembly after the United States used its veto in the Security Council to block the resolution on June 1.
The text was put forward by Algeria and Turkey on behalf of the Arab League and the Organization of Islamic Cooperation.
The General Assembly last held a similarly contentious vote on the Israeli-Palestinian conflict in December, when it rejected President Donald Trump's decision to recognize Jerusalem as Israel's capital and move the US embassy there.