Rosen, who most recently served as the deputy secretary at the Department of Transportation, was confirmed along party lines by a vote of 52 to 45 in the Republican-controlled Senate.
Rosen will replace Deputy Attorney General Rod Rosenstein, whose last day at the Justice Department was May 11.
The job of deputy attorney general is usually relatively low-profile. That was not the case for Rosenstein, who became the center of attention in May 2017 when he appointed former FBI Director Robert Mueller as special counsel to probe whether Trump’s presidential campaign colluded with Russia to tilt the election in his favor.
The investigation, which concluded in March with Mueller finding insufficient evidence of a criminal conspiracy between Trump’s campaign and Russia, has dogged Trump’s presidency and continues to be a political lightning rod that has deeply divided Republicans and Democrats.
As deputy attorney general, Rosen will oversee the day-to-day operation of an agency that employs more than 100,000 people at prosecutors’ offices, federal prisons and FBI offices across the country.
Rosen has no experience as a prosecutor, a fact that Democrats have said should disqualify him from the job.
“At this critical moment, we need a deputy attorney general who knows the Justice Department, who has experience in criminal investigations and prosecutions, and who is committed to the Department’s role of enforcing the law independently,” U.S. Senate Democratic Whip and Senate Judiciary Committee member Dick Durbin said in a statement.
In addition, some Senate Democrats have said they fear that Rosen will be too partisan – a concern that has intensified since the Mueller report’s release.
Democrats have accused Barr of misleading people about the report’s findings and acting more like Trump’s personal lawyer than the American public’s lawyer.
Rosen had worked at the White House budget office under Republican President George W. Bush.
Bush nominated him to be a federal judge, but Rosen did not get a confirmation vote in the Senate, which was under Democratic control at the time.
Reporting by Sarah N. Lynch and Andy Sullivan; Editing by Bernadette Baum, Jonathan Oatis and Bill Berkrot