Donald Trump has chosen William Barr to be the new US attorney general, a position he previously held in the 1990s.
If confirmed by the Senate, Mr Barr would replace Jeff Sessions, who was fired by Mr Trump a month ago.
The role would put him in charge of the federal probe into Russian election interference.
Mr Barr was "my first choice from day one," and "a terrific man, a terrific person, a brilliant man," the US president told reporters outside the White House.
Mr Barr, a lawyer who was previously attorney general from 1991 to 1993 under President George HW Bush, has defended Mr Trump's controversial decision to fire then-FBI Director James Comey in May 2017 when Mr Comey was leading the Russia probe.
After Mr Comey's firing, Special Counsel Robert Mueller took over the investigation, which includes any possible collusion between Moscow and Mr Trump's 2016 election campaign and any potential obstruction of justice.
Mr Barr has said there is more reason to investigate potential wrongdoing by Hillary Clinton than there is to probe any potential collusion.
As attorney general, Mr Barr would have ultimate responsibility for the Russia probe, unless he recuses himself. Mr Sessions recused himself from overseeing the investigation.
US intelligence agencies have concluded Moscow worked to influence the election and tip it in Mr Trump's favour. Russia has denied any interference.
Mr Barr’s nomination could stir opposition from Senate Democrats but is unlikely come up for a vote until next year. Republicans will control the chamber with a 53-47 majority in the new Congress convening in January.
