Attorney General William Barr has considered quitting over President Trump's tweets about the Justice Department, two sources familiar with the situation confirmed to CBS News on Tuesday. Last week, Barr told ABC News the president's tweets make it "impossible" for him to do his job, a clear message to the president after the Justice Department decided to back off on a seven-to-nine-year sentence recommendation for longtime Trump ally Roger Stone.

The Washington Post first reported that Barr was considering resigning.

Justice Department spokeswoman Kerri Kupec denied any plans to resign on Twitter, writing, "Addressing Beltway rumors: The Attorney General has no plans to resign." White House press secretary Stephanie Grisham echoed Kupec's tweet, also on Twitter.

It is unclear how serious Barr's consideration of quitting has been.

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The president has used Twitter to declare the initial sentencing recommendation for Stone a "miscarriage of justice," and offered his opinion in other sensitive Justice Department matters. The president praised Barr on Twitter for intervening in Stone's case, although Barr insists he did not speak to the president about Stone's sentencing recommendation. The president appeared undeterred by Barr's request.

""The President has never asked me to do anything in a criminal case." A.G. Barr This doesn't mean that I do not have, as President, the legal right to do so, I do, but I have so far chosen not to!" Mr. Trump wrote after the ABC interview.

“The President has never asked me to do anything in a criminal case.” A.G. Barr This doesn’t mean that I do not have, as President, the legal right to do so, I do, but I have so far chosen not to! — Donald J. Trump (@realDonaldTrump) February 14, 2020

All four federal prosecutors in Stone's case withdrew from it after the Justice Department suggested the seven-to-nine-year recommendation they'd made was too tough.

Barr has long been criticized for his perceived defense of the president, ever since he characterized then-special counsel Robert Mueller's report without offering a full picture of Mueller's findings. Barr's critics have suggested he still aims to protect the president, and that his recent protests are for show.

Mr. Trump has long used Twitter to pressure his attorneys general, repeatedly attacking former Attorney General Jeff Sessions, who sparked the president's ire by recusing himself from the Mueller investigation. Mr. Trump never got over Sessions' recusal, and the attorney general eventually left his post after the 2018 midterm elections.