Barr will replace Jeff Sessions, who was forced to resign by Trump last month over displeasure with his performance and over the Russian election interference investigation by Special Counsel Robert Mueller.
In announcing the nomination, Trump described Barr as "a terrific man, a terrific person."
"He was my first choice from day one.... respected by Republicans, respected by Democrats," he told reporters.
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Barr critical of Russia probeThe conservative lawyer served as attorney general from 1991 to 1993 under the late President George H.W. Bush.
The 68-year-old has defended Trump's controversial decision to fire former FBI Director James Comey in May 2017 when Comey was leading the Russia investigation, which is also looking into whether there was collusion with Trump's campaign.
Barr has said there is more reason to probe Trump's former opponent, former Secretary of State Hillary Clinton, than to look into any possible collusion with Trump's 2016 campaign. He has also accused Mueller's investigation of not being impartial.
As attorney general, Barr would head the Justice Department, which is overseeing Mueller's investigation.
US intelligence agencies concluded that Russia worked to influence the 2016 US presidential election and to tip public opinion in Trump's favor. Trump has repeatedly slammed the investigation as a "witch hunt," with Russia denying any wrongdoing.
Barr would still need to be approved by the Republican-controlled Senate, but a vote on confirming him would likely not take place until next year.
rs/rt (Reuters, AFP, dpa, AP)
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