US Under Secretary of State for Political Affairs Wendy Sherman leaves after a meeting in this February 22, 2015, file photo in Geneva. (AFP)
The top US negotiator in talks with Iran on curtailing its nuclear program will leave her post after a June 30 deadline for an agreement, according to The New York Times.
Wendy Sherman, 65, broke the news to staffers on Wednesday then left on her latest trip for talks with Iran in Switzerland, the paper said.
"It's been two long years," the Times quoted Sherman as saying. Her post is under secretary of state for policy.
It added that, with the departure of Sherman, all the top US officials who have negotiated with Iran over that span will have left President Barack Obama's administration.
"In Wendy Sherman, couldn't have had a better partner. Lots of work left for her, including with Iran, but wishing her well on the next chapter," National Security Advisor Susan Rice tweeted.
On Saturday, US Secretary of State John Kerry will once again meet Iranian counterpart Mohammad Javad Zarif in Geneva, after weeks of behind-the-scenes technical discussions in Vienna seeking to narrow the gaps on what would be an unprecedented deal on curtailing Iran's nuclear program.
Iran and the six global powers leading the talks, Britain, China, France, Germany, Russia and the United States, laid down a framework to guide the final accord in eight days of marathon late-night talks in Lausanne in early April.
Kerry and his team will now return to Europe for what is expected to be a final series of meetings with Zarif as the clock ticks down to June 30 and a possible deal putting a nuclear bomb beyond Iran's reach for longer.