Sen. John Kennedy, R-La., warned President Trump on Sunday against tweeting about criminal cases like he did with the one involving Republican operative and Trump ally Roger Stone.

Speaking on CBS’ “Face The Nation,” Kennedy said that the president has every right to tweet out his thoughts, but that doesn’t mean he should. He also said Trump should heed the advice of Attorney General William Barr and refrain from jumping on social media to discuss the case.

“Just because you can sing, though, doesn’t mean you should sing,” Kennedy said. "This is a case where tweeting less would not cause brain damage.”

BARR SAYS TRUMP TWEETS 'MAKE IT IMPOSSIBLE TO DO MY JOB' AMID ROGER STONE DRAMA

Kennedy’s comments came days after Barr himself publicly swiped at Trump, declaring on Thursday that the president’s tweets about Justice Department prosecutors and open cases “make it impossible for me to do my job.”

Barr made the comment during an interview with ABC News just days after his Justice Department overruled its own prosecutors — who had recommended in a court filing that Stone be sentenced to 7 to 9 years in prison — and took the extraordinary step of lowering the amount of prison time it would seek. The department didn't offer an amended number.

Barr himself has been under fire for the reversal. Still, it was a highly unusual move for a member of the Cabinet to criticize the president — especially a Trump loyalist who shares the president's views on expansive executive powers. Thursday's comment served as a defense of his own integrity — an effort to salvage his own reputation and that of the Department of Justice by publicly rebuking the president he has propped up from Day One of his tenure.

The remarks, made so quickly after the decision to back away from the sentencing, suggested Barr was aware the reversal had chipped away at the department's historic reputation for independence from political sway. But he stopped short of acknowledging wrongdoing by anyone.

White House Press Secretary Stephanie Grisham said Trump “wasn’t bothered by the comments at all and he has the right, just like any American citizen, to publicly offer his opinions.” She added, “The president has full faith and confidence in Attorney General Barr to do his job and uphold the law.”

Barr said Trump's tweets created perception problems for the department that called into question its independence, but he denied there was any order from Trump and said Trump's tweets did not factor into the decision.

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Earlier in the week, Trump applauded Barr on Twitter for the decision to reverse the sentencing recommendation, writing: “Congratulations to Attorney General Bill Barr for taking charge of a case that was totally out of control and perhaps should not have even been brought.”

The department insisted the decision to undo the sentencing recommendation was made Monday night — before Trump blasted the recommendation on Twitter as “very horrible and unfair”— and prosecutors had not spoken to the White House about it. The about-face prompted the four attorneys who prosecuted Stone to quit the case. One left the Justice Department altogether.

“I’m happy to say that, in fact, the president has never asked me to do anything in a criminal case,” Barr said in the ABC interview. “However, to have public statements and tweets made about the department, about our people ... about cases pending in the department, and about judges before whom we have cases, make it impossible for me to do my job and to assure the courts and the prosecutors in the department that we’re doing our work with integrity.”

The Associated Press contributed to this report.