AP Photo/Ahn Young-joon
"With her departure, all the top officials who have negotiated with Iran over those two years will have left the administration, leaving questions about who will coordinate the complex process of carrying out a deal if one is struck by the deadline," The Times notes.
Sherman made her intentions known before leaving for Vienna and Geneva for a last round of talks aimed at securing curbs on Iran's nuclear program in return for lifting sanctions that have crippled the country's economy, the newspaper said.
"It's been two long years," the Times quoted Sherman as saying, referring to the protracted and intensely complex discussions with the Iranians that began with secret talks between the two long-time foes.
Sherman, who is under secretary of state for political affairs at the State Department and who has white, close-cropped hair, has stood out as one of the few women in a sea of men in dark suits at most of the negotiating sessions.
Her departure will leave a big gap in the U.S. team, which will have to manage the arrangements for rolling back sanctions and monitoring Iran's compliance should a final deal be struck next month.
"Administration officials are concerned that with the departures of Ms. Sherman, Mr. Burns and Jake Sullivan, one of Mrs. Clinton's top aides, much of the historical memory about the Iran deal could be lost," the Times reported.
Secretary of State John Kerry said in a statement to CNN: "Wendy has been an absolutely critical member of my team, most notably in her work spearheading the nuclear negotiations with Iran, but on nearly every important issue that has crossed my desk."
(Editing by Robert Birsel)