Federal Judge Amy Berman Jackson, who last week sentenced longtime GOP operative Roger Stone to more than three years in prison, on Tuesday expressed concern for the safety of a juror from Stone’s trial after President Donald Trump repeatedly accused her of being biased.

“The president of the United States used his Twitter platform to disseminate a particular point of view about a juror,” Jackson said during a hearing in Washington, D.C. “Any attempt to invade the privacy of the jurors or to harass or intimidate them is completely antithetical to our system of justice. They deserve our protection. They deserve to have their privacy protected.”

Judge Jackson convened Tuesday’s hearing to consider a sealed motion for a new trial filed by Stone’s defense counsel, who cited alleged jury misconduct. As afternoon turned into evening, Jackson called jurors from Stone’s trial to the stand to face questioning – including the foreperson, who Trump has accused of being biased.

Meanwhile, Trump, while returning from his visit to India aboard Air Force One, dug in on criticism of the judge and the jury foreperson, calling her “totally biased, as is the judge.”

The president sent his tweet just moments after Jackson took note of his prior tweets – and as the hearing was going on.

Stone, 67, was convicted of misleading congressional investigators on several key elements of their probe into Russian meddling in the 2016 election, including communications he had with the Trump campaign about the WikiLeaks dissemination of damaging documents stolen from Democrats.

Stone was making a bid for a new trial just days after Judge Jackson sentenced him to 40 months in prison amid speculation about a possible pardon from President Donald Trump.

While details of both the request for a new trial and the Justice Department's subsequent opposition to the defense motion are mostly unknown because they're under seal, President Trump has claimed the jury was "totally tainted" and has called the jury forewoman "anti-Trump."

In a surprise move on Tuesday, Judge Jackson called the jury foreperson and two other jurors to the stand to answer questions about how the jury conducted its work – and whether the foreperson misled the court during jury selection.

Asked whether her social media activity during the trial was meant as a celebration of “the verdict that was yet to be delivered in the Roger Stone case,” the foreperson responded, “absolutely not.”

Legal experts say this sort of late-in-the-game motion for a new trial based on jury misconduct is a tall order for defense counsel.

“The standard to prove juror misconduct is quite high,” said ABC News Chief Legal Analyst Dan Abrams. “The key when it comes to juror misconduct is just that – juror misconduct. Lying, misleading, violating court orders. That’s typically where you’d see something like this occur.”

Earlier this month, unsealed court documents revealed that Judge Jackson denied a previous sealed motion for a new trial filed by Stone's defense team involving a post-trial objection to one of the jurors. The individual disclosed during the jury selection process that they had a legal background and had worked for the IRS.

President Trump last week addressed the sentencing of Stone, his longtime friend who briefly served as a campaign adviser in 2015, saying that what happened to him is "unbelievable" but stopping short of saying whether he would issue a pardon.

"I'm following this very closely and I want to see it play out to its fullest because Roger has a very good chance of exoneration in my opinion," Trump said.

He went on to express his grievances with the forewoman of the jury, who came under scrutiny for social media posts she allegedly published prior to serving on Stone's jury. The activity was publicly reported just days before Stone's attorneys filed their most recent sealed motion for a new trial citing juror misconduct. The content was later removed.

Trump said the jury forewoman was an "anti-Trump person totally."

"It's my strong opinion that the forewoman of the jury, the woman who was in charge of the jury was totally tainted," he added.

According to the terms of Stone's sentencing, he is to voluntarily turn himself in to authorities to begin his prison term within two weeks of Judge Jackson ruling on his bid for a new trial. Judge Jackson ended Tuesday's hearing without reaching a decision, saying she would take the matter under advisement.