Rod Rosenstein, the U.S. attorney in Maryland, is expected to be nominated as deputy attorney general. If confirmed in the No. 2 spot at the Justice Department, Rosenstein would head up any investigation into Hillary Clinton, after Trump's choice for attorney general, Senator Jeff Sessions, said during his confirmation hearing on Tuesday that he would recuse himself from any Clinton-related matters.

Clinton was the subject of a federal investigation into her use of a private email server while Secretary of State that ended without any charges being filed.

As the deputy attorney general, Rosenstein, who must be confirmed by the Senate, would be responsible for the day-to-day running of the sprawling department of about 113,000 employees with its 94 districts, essentially becoming its COO. The heads of several agencies - including FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosives, would report to him.

Rosenstein, 52, was appointed to his current post by Republican President George W. Bush in 2005, and remained there during the administration of President Barack Obama. A Harvard law graduate, Rosenstein joined the Justice Department in 1990 as a trial attorney in the criminal division’s public integrity section.