Michael McFaul, U.S. ambassador to Russia, leaves the Foreign Ministry in Moscow in this May 15, 2013, file photo. (Misha Japaridze/AP)

U.S. Ambassador Michael McFaul, the architect of President Obama’s effort to reset American relations with Russia, said Tuesday that he will leave his post at the conclusion of the Olympics to return to Stanford University.

McFaul, who has been ambassador for two years, said he was resigning to rejoin his family, who returned to California last year so that his older son could finish his high school years at home.

“We tried to make a [5,600-mile] commute work for our family,” he wrote in a blog post. “But after seven months of separation, I simply need to be with my family again.”

McFaul never wavered in his defense of the “reset” despite the increasingly rocky trail of U.S.-Russian relations in recent years. In a blog post titled “It’s Time, My Friend, It’s Time,” written in Russian and English, which he said would be his last as ambassador, he listed what he argued were the reset’s accomplishments.

Among them were the New START accord limiting nuclear arms, the opening of the Northern Distribution Network allowing the United States to send supplies to its troops in Afghanistan by way of Russia, cooperation on Iran and North Korea, and Russia’s accession to the World Trade Organization — which Washington wanted on the grounds that it requires Russia to commit to international trade rules.

Yet all of those accomplishments were completed — or headed toward completion — while McFaul was Obama’s chief national security adviser on Russia, before he came to Moscow as ambassador.

[Read: How McFaul has gotten his message out]

McFaul arrived in January 2012, as Vladimir Putin was well on his way to reclaiming the Russian presidency. Putin’s campaign relied heavily on anti-Americanism, and much of that fell on McFaul.

He acknowledged in his blog post that there have been challenges to manage during his two years here: the expulsion of the U.S. Agency for International Development, the ban on adoptions by Americans, the haven provided to Edward Snowden, a virulent anti-Americanism in the Russian media, and fundamental disagreements over Syria and, most recently, Ukraine.

The initial accomplishments of the reset in relations, which McFaul put together as a White House aide, had provided no momentum toward a broader warming in ties between Moscow and Washington — and as ambassador he had to work with the consequences.

The chief factor was the return of Putin to the Kremlin. The Russian president had not forgotten that McFaul once edited a book on Ukraine’s Orange Revolution of 2004 — which for Putin was a personal disaster that he blamed on American interference and that he vowed would never be replicated in Russia.

Before working at the White House, McFaul, 50, was an academic, writing extensively on democracy in this part of the world. That was enough for Putin and other officials to consider McFaul a provocateur. He was greeted with suspicion and even malevolence, as if sent by Secretary of State Hillary Rodham Clinton to fan the fires of revolution and encourage unwelcome democratic initiatives.

Not content to slip into the background, he was followed by hostile television crews, who harassed not only him but the people he met with if they happened to be involved with the human rights movement or the political opposition. McFaul pressed on, undeterred, almost invariably good-humored, except for one encounter in which he told a particularly aggressive pack that they represented a “wild” country.

He did become an indefatigable contributor to Twitter, writing about issues as varied as support for democracy and his broken finger, and he developed a following of 60,000.

At the White House, Ben Rhodes, the national security spokesman, said Obama was “deeply grateful” for McFaul’s service.

“Mike has been tireless in advocating for the universal values that America stands for around the world, reaching out to civil society, and recognizing the right of every voice to be heard,” Rhodes said.

In his blog post, McFaul said he originally had promised his older son that he would be away from his California school for two years, a promise not kept.

“After five years away, first in Washington and then Moscow,” he wrote, “he wanted to go home for his last years of high school. We all agreed that it was in his best interest to return, and that decision turned out to be the right one.

“For the immediate future,” he wrote, “my base of operations will be Stanford University. But a part of me — an emotional part, an intellectual part, a spiritual part — will always remain in Russia. That was true before I joined the government. It will remain so forever after.”