Donald Trump plans to nominate Jeffrey Rosen as the next deputy US attorney general, a senior administration official said on Tuesday night.

Rosen, the deputy secretary of the Department of Transportation, would succeed Rod Rosenstein, who after the firing of the FBI director James Comey appointed special counsel Robert Mueller to investigate possible ties between Russia and Trump’s campaign.

Rosenstein is expected to step down by mid-March, a justice department official said on Monday.

The attorney general, William Barr, welcomed the choice of the new deputy, saying in a statement that Rosen had 35 years of experience at the highest levels of government and in the private sector.

“His years of outstanding legal and management experience make him an excellent choice to succeed Rod Rosenstein, who has served the Department of Justice over many years with dedication and distinction,” Barr said.

The transportation secretary, Elaine Chao, said Rosen had played a critical role in her department.

“I will be sorry to lose him, but I am confident that he is the right lawyer to help the new Attorney General succeed at the Justice Department, for the benefit of the American people,” she said in a statement.

Rosen’s nomination must be confirmed by the US Senate.