The U.S. Senate was set to approve President Donald Trump’s attorney general nominee William Barr on Thursday, putting the veteran Republican lawyer in charge of Special Counsel Robert Mueller’s probe of any ties between Trump’s campaign and Russia.

Many Democrats were expected to oppose Barr out of concern he might not fully make public Mueller’s findings. But the Senate is controlled by Trump’s fellow Republicans, so Barr’s confirmation was virtually assured.

Previously attorney general from 1991 to 1993 under President George H.W. Bush, Barr has won praise from lawmakers in both parties for his expertise and grasp of the workings of the Justice Department, which he would head.

He would be the third man in barely two years to occupy that post, replacing acting Attorney General Matthew Whitaker, who replaced Attorney General Jeff Sessions. Trump ousted Sessions last November after criticizing him repeatedly.

Mueller is investigating meddling by Russia in the 2016 U.S. presidential election and whether Moscow colluded with Trump’s campaign to try to tilt the election in Trump’s direction, as well as possible obstruction of justice.

Trump denies any collusion. The Kremlin denies any meddling.

Before being nominated, Barr wrote a 19-page legal memo, which he shared with Trump’s legal team and Justice Department officials. It called Mueller’s probe “fatally flawed.”

Barr has said he will not let himself be bullied by Trump and will protect the integrity of Mueller’s investigation and make public as many of its findings as he can.

Barr has not promised to release Mueller’s report in its entirety. He has warned he may not be allowed to reveal the identities of people who escape prosecution. That stance troubles many Democrats, who say Barr’s expansive views of executive power might lead him to suppress parts of the report.

Despite Democrats’ opposition, many are still anxious to have Barr installed quickly so that he can replace Whitaker, whose tenure has been fraught with controversy since Trump installed him in November.

Critics have alleged Whitaker’s appointment was unlawful. Democrats fear Trump installed Whitaker to undermine Mueller’s probe because Whitaker had criticized it when he was a conservative pundit.

Barr is widely expected to back many of Trump’s tough immigration policies. He will also be under the microscope for how he implements a new law that eases prison sentences for non-violent criminals, after he advocated for the opposite, tough-on-crime approach for decades.

(Reporting by Sarah N. Lynch and Andy Sullivan; Editing by Kevin Drawbaugh and Peter Cooney)