Weighing in even as a Virginia jury deliberates for a second day, U.S. President Donald Trump on Friday called the bank and tax fraud trial of his former campaign chairman Paul Manafort "very sad" and described the defendant as a "very good person."

Manafort's trial in federal court in Alexandria is the first stemming from Special Counsel Robert Mueller's 15-month-old investigation of Russia's role in the 2016 U.S. election, Reuters said.

U.S. District Judge T.S. Ellis, presiding over the case, said he personally had received threats related to the trial and was being protected by U.S. marshals. The judge also rejected a motion by some news organizations to make public the names of the jurors, saying he was concerned about the jury's "peace and safety."

"I had no idea this case would excite these emotions ... I don't feel right if I release their names," the judge said.

In an indication that the six women and six men of the jury may not reach a verdict on Friday, they sent the judge a note asking that they be permitted to finish their work for the day at 5 p.m. (2100 GMT) because one juror has a social engagement.

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In remarks to reporters at the White House, Trump again called Mueller's investigation, which had cast a cloud over his presidency, a "rigged witch hunt," but sidestepped a question about whether he would issue a presidential pardon for Manafort.

"I think the whole Manafort trial is very sad, when you look at what's going on there. I think it's a very sad day for our country," Trump said.

"He worked for me for a very short period of time. But you know what? He happens to be a very good person. And I think it's very sad what they've done to Paul Manafort."

Trump made his comments while the jurors deliberated behind closed doors on Friday morning. The jurors met for about seven hours on Thursday without reaching a verdict on 18 criminal counts with which Manafort is charged.

As president, Trump has the power to pardon Manafort on the federal charges. He has already issued a number of pardons, including for a political ally, former Arizona sheriff Joe Arpaio. Asked by a reporter on Friday if he would pardon Manafort, Trump said, "I don't talk about that now."

The charges largely predate Manafort's five months working on Trump's campaign during a pivotal period in the 2016 presidential race, including three months as campaign chairman.

Manafort, 69, faces five counts of filing false tax returns, four counts of failing to disclose his offshore bank accounts and nine counts of bank fraud. If convicted on all counts, he could spend the rest of his life in prison.

Prosecutors accused Manafort of hiding from U.S. tax authorities $16 million in money he earned as a political consultant for pro-Russian politicians in Ukraine to fund an opulent lifestyle and then lying to banks to secure $20 million in loans after his Ukrainian income dried up and he needed cash.