Sergey Kislyak was a frequent visitor to the White House when Obama was in office.
From the Daily Caller:
The visitor logs, which Obama made public in 2009 in a push for transparency, show that the long-time Russian ambassador to the United States visited the White House at least 22 times between 2009 and 2016.Scandalous!
Kislyak appeared in the logs as recently as September 2016 when he had a meeting scheduled with one of Obama’s senior advisers, John Holdren, in the Eisenhower Executive Office Building.
...Kislyak was also listed on the logs in July 2016, March 2016, January 2016, August 2015, April 2014, February 2014, May 2013, February 2013, November 2012, December 2011, July 2011, December 2010, October 2010, May 2010, April 2010, February 2010, March 2010, December 2009 and September 2009.