Maryland Sen. Chris Van Hollen said Wednesday that the departure of Deputy Attorney General Rod Rosenstein would threaten Robert Mueller's Russia investigation at a time when the integrity of the Justice Department "is under assault" by President Donald Trump.
"I'm very concerned about the news that he may leave," Van Hollen, a Democrat, said in an interview. "He has played a key role in protecting the integrity and independence of the Mueller investigation."
Multiple news outlets reported Wednesday that Rosenstein, the former U.S. attorney for Maryland, was expected to leave his position after Trump's attorney general nominee, William Barr, is confirmed by the Senate. There was no confirmation by the Justice Department. nor a clear timeline for when Rosenstein may step down.
Van Hollen said the departure of Rosenstein, the second-ranking Justice Department official, would be particularly troubling because of concerns about Barr's independence.
Barr "has called into question the legitimacy of the Mueller investigation, so I don't think he can be trusted to be an impartial overseer of the investigation," Van Hollen said.
Barr sent an unsolicited memo to the Justice Department last year sharply critical of the portion of Mueller's probe focusing on potential obstruction of justice by Trump, the Wall Street Journal reported in December.
Justice Department spokeswoman Kerri Kupec said in a statement Wednesday that Barr acted on his own initiative. “Those views were based solely on publicly available information,” she said. “Following the announcement of Mr. Barr’s nomination, senior Department ethics officials were consulted and advised that, under the applicable rules of professional conduct, Mr. Barr’s memo would present no conflict as to his duties as Attorney General. Mr. Barr has stated that, if confirmed, he will make any decisions based on the actual facts and circumstances of any particular matter.”
But Van Hollen said he was concerned that Barr, through his memo, had been "trying to ingratiate himself with President Trump and say, 'Look at me, I can do your bidding at the Justice Department.’ "
Rosenstein oversees the Mueller investigation into possible collusion between Russians and Trump associates during the 2016 presidential campaign.
Rosenstein had been Maryland's U.S. attorney for 12 years when he left his office in Baltimore to serve as the No. 2 to Attorney General Jeff Sessions. Sessions ordinarily would have overseen the Russia investigation but recused himself because of his close involvement in the Trump campaign.
Sessions was ousted by Trump in November. Matthew Whitaker, Sessions' former chief of staff, has been running the department since then as acting attorney general.
Maryland attorney general Brian Frosh — in a pending court case -- has sought the removal of Whitaker on grounds that his holding the post violates the Constitution’s appointments clause.
Rosenstein's tenure was imperiled last year after a New York Times report that he discussed invoking the 25th amendment, which outlines a method to remove an unfit chief executive. Rosenstein said the report was not accurate.
Van Hollen and Maryland Sen. Ben Cardin, also a Democrat, supported and introduced Rosenstein during his confirmation hearing in March 2017 by the Senate Judiciary Committee.
Rosenstein, who has served with Republican and Democratic administrations, said at the hearing that political affiliation "is irrelevant to my work."
Van Hollen said Wednesday that Rosenstein “has tried to protect the integrity of the institution of the Justice Department at a time when it is under assault by the president of the United States.”