The United States objected on Friday to United Nations Secretary-General Antonio Guterres' choice of former Palestinian prime minister Salam Fayyad as the body's new representative to Libya.
It was unclear whether the objection, expressed in a statement by Nikki Haley, the United States ambassador to the United Nations, Haley, had ended Fayyad's candidacy.
The United States wields significant influence as one of the five permanent members of the UN Security Council.
No one was immediately available from the secretary-general's office for comment.
"The United States was disappointed to see a letter indicating the intention to appoint the former Palestinian Authority Prime Minister to lead the UN Mission in Libya," Haley said in her statement.
"For too long the UN has been unfairly biased in favour of the Palestinian Authority to the detriment of our allies in Israel," she said.
Haley added that the United States "does not currently recognise a Palestinian state or support the signal this appointment would send within the United Nation."
The US ambassador said Washington encouraged Israel and the Palestinians "to come together directly on a solution" to end their conflict.
Fayyad, a Texas-educated former International Monetary Fund official, was prime minister of the Palestinian Authority from 2007 to 2013. He had earned praise in the international community for his efforts to crack down on corruption and to build effective Palestinian public institutions.
Guterres selected Fayyad to take over as Libya envoy from Martin Kobler, a German diplomat who has served as the UN representative since November 2015.