(CNN) -- An architect of the Obama administration's "reset" policy with Russia says he will step down as the American ambassador to the country later this month.
Michael McFaul, U.S. ambassador to Russia since January 2012, announced Tuesday he'll leave the post shortly after the Winter Olympics conclude in the southern Russian resort town of Sochi.
McFaul has been a controversial figure in Russia, with some state-run media viewing him with suspicion for his outspoken support of pro-democracy groups. But in his online journal, McFaul said Tuesday that he would miss the job, stressing he was leaving for family considerations.
McFaul said his wife and two sons moved back to California last summer because his oldest son wanted to be home for the last few years of high school.
"We tried to make a 9,000 kilometer commute work for our family. But after seven months of separation, I simply need to be with my family again," McFaul wrote.
"I will leave Russia reluctantly," he said. "I love this job. It is a tremendous honor to represent my country here. I will miss interacting with my partners in the Russian government and with Russians from all sectors of society."
As a Stanford University political science professor, McFaul became one of the best-known American experts on Russia. After advising then-Sen. Barack Obama on Russia during the 2008 presidential campaign, McFaul took a leave from Stanford to become senior director for Russia and Eurasian affairs at the National Security Council.
He helped develop the U.S. "reset" policy with Russia, after which the countries signed the New START arms control deal and agreed on a transit treaty allowing the United States and NATO to use a route through Russia into Afghanistan.
On his arrival in Moscow as ambassador in 2012, he got a rough reception from government-controlled media. An analyst on a government network said McFaul was a "specialist purely in the promotion of democracy" and suggested his agenda was dedicated to supporting opposition leaders in the country.
That criticism came as protesters in Moscow were rallying against then-Prime Minister Vladimir Putin, who was running again for president. Putin, who went on to win the presidency, accused the U.S. State Department of stirring things up.
McFaul's ambassadorship came at a time of strained relations between the two countries, with quarrels over, among other things, Syria's civil war and the arrival in Moscow of admitted National Security Agency leaker Edward Snowden.
U.S. Deputy National Security Adviser Ben Rhodes said Tuesday that President Obama "is deeply grateful for Ambassador McFaul's extraordinary service over the last five years."
"From the White House to Spaso House (the U.S. Embassy in Moscow), Mike helped shape policies that advanced America's interest -- from the New START treaty, to resupplying our troops in Afghanistan; from sustaining U.S.-Russian cooperation on negotiations with Iran, to deepening trade and commercial ties," Rhodes said.
CNN first learned of McFaul's planned departure on Twitter.
CNN's Jill Dougherty and Jason Hanna contributed to this report.