MOSCOW (AP) — U.S. Ambassador Michael McFaul, the architect of President Barack Obama’s effort to reset relations with Russian, announced on Tuesday that he is stepping down after two turbulent years in Moscow.

McFaul, a Stanford University professor who signed on as an unpaid adviser to Obama during his first presidential campaign, moved with him to Washington and served for three years on the National Security Council before taking up his first diplomatic post as ambassador to Russia.