Nigeria's former finance minister Ngozi Okonjo-Iweala had been on course to lead the World Trade Organization.
But the race to find a director-general for the global trade watchdog was plunged into uncertainty on Wednesday (October 28) after an intervention from the United States.
Okonjo-Iweala is the preferred choice of three WTO ambassadors tasked with finding a successor to Roberto Azevedo.
They cite her widespread, cross regional backing.
But the United States supports another candidate - South Korean trade minister Yoo Myung-hee.
And with the decision requiring consensus, any of the WTO's 164 members can block the appointment.
Keith Rockwell is a spokesman for the WTO.
"The US said that they supported minister Yoo because of her 25 years of trade experience, that she would be able to hit the ground running. They said that they could not endorse Doctor Ngozi. I don't know the reasons for that, you'll have to ask them."
The U.S. is, in effect, threatening to render the WTO leaderless for weeks or months to come and it's not the first time it's been a thorn in the side of the trade body.
Washington has already paralyzed the WTO's role as global arbiter on trade by blocking appointments to its appeals panel.
U.S. President Donald Trump describes the watchdog as "horrible" and biased towards China.
He faces a presidential election in less than a week and is trailing in national polls.
The WTO has scheduled a meeting to try and secure the required backing for Okonjo-Iweala's appointment, six days after the election.
By that time, Trump may be on his way out of the White House but it was not immediately clear if that would affect the U.S. position on her appointment.