On Wednesday, a WTO nominations committee recommended the group’s 164 members appoint Ngozi Okonjo-Iweala.
She would be the first woman and first African to lead the WTO.
But the US, critical of the WTO’s handling of global trade, wants another woman, South Korea’s Yoo Myung-hee, saying she could reform the body.
Ms Okonjo-Iweala said she was “immensely humbled” to be nominated.
But the four-month selection process to find the next WTO director-general hit a road block when Washington said it would continue to back South Korea’s trade minister.
In a statement critical of the WTO, the Office of the US Trade Representative, which advises President Donald Trump on trade policy, said the organisation “must be led by someone with real, hands-on experience in the field”.
Ms Yoo had “distinguished herself” as a trade expert and “has all the skills necessary to be an effective leader of the organisation”, the statement said.
It added: “This is a very difficult time for the WTO and international trade. There have been no multilateral tariff negotiations in 25 years, the dispute settlement system has gotten out of control, and too few members fulfill basic transparency obligations. The WTO is badly in need of major reform.”
Earlier on Wednesday, after a WTO delegates meeting to discuss the appointment, spokesman Keith Rockwell said just one member country did not support Ms Okonjo-Iweala.
“All of the delegations that expressed their views today expressed very strong support for the process… for the outcome. Except for one,” he said. – BBC