No more speculation.
Via Fox News:
Deputy Attorney General Rod Rosenstein is expected to leave his role at the Justice Department by mid-March, a senior DOJ official told Fox News on Monday.
An official announcement of who has been selected to replace Rosenstein could come as early as this week. A Trump administration official added that Attorney General William Barr has picked Jeffrey Rosen, who currently serves as Deputy Secretary of the U.S. Department of Transportation, to take over for Rosenstein.
A graduate of Northwestern University and Harvard Law School, Rosen previously served as General Counsel and Senior Policy Advisor for the White House Office of Management and Budget (2006 to 2009) and as General Counsel at the Department of Transportation (2003 to 2006), according to his online biography.