Marc Grossman, the special U.S. envoy to Afghanistan and Pakistan, in Copenhagen in March. (Jens Dresling/AP)

Grossman, who had previously served as undersecretary for political affairs, assistant secretary for Europe and ambassador to Turkey, was persuaded to put a second career at the Cohen Group on hold to take the SRAP position after Richard C. Holbrooke, who had inaugurated the job, died in December 2010.

The SRAP job is one of several senior envoy positions the Obama administration created to coordinate particularly vexing diplomatic challenges that spanned several countries. Former senator George Mitchell, who served as special envoy for Middle East Peace, was replaced last year by David Hale, a senior foreign service officer.

Grossman, who plans to return to private life, will be replaced in an acting capacity by his current deputy, David D. Pearce. Before moving to the SRAP office early this year, Pearce served as assistant chief of mission at the U.S. Embassy in Afghanistan and was ambassador to Algeria.