The jury in the tax and fraud trial of Donald Trump's former campaign chief Paul Manafort resumed their deliberations today, as the president weighed in on the closely watched case, calling it a "sad day for our country." The judge said he was optimistic that there could be a verdict "soon" as the jury began a second day of deliberations. Trump, meanwhile, said Manafort "happens to be a very good person" who worked for him "for a very short period of time." "I think it's very sad what they've done to Paul Manafort," the president told reporters. Manafort, 69, is accused of providing fraudulent statements to secure bank loans and failing to pay taxes on tens of millions of dollars he earned while advising Russian-backed politicians in Ukraine between 2006 and 2015. "You may deliberate as long or as little as you wish," Judge T.S. Ellis told the six-man, six-woman jury weighing the 18 charges against the once high-flying Republican political consultant. After the jury filed out of the courtroom in Alexandria, Virginia, the judge addressed prosecutors, defense attorneys and the public. "I think we're optimistic that the case might end soon," Ellis said. The case stems from Special Counsel Robert Mueller's investigation into Russian interference in the 2016 presidential election. Manafort is not charged with any crimes related to his brief time as Trump's campaign chief, but the trial is seen as an important test for the Mueller probe. Trump has repeatedly denounced the Mueller probe as a political "witch hunt" and denied there was any collusion with Moscow to help him defeat Democrat Hillary Clinton. The case went to the jury this morning after 12 days of riveting testimony featuring hidden bank accounts, betrayal and lavish spending on homes, cars and clothes. Prosecutors outlined schemes allegedly used by Manafort to avoid paying US taxes on the millions of dollars he earned in Ukraine and deposited in bank accounts in Cyprus. Defence attorneys sought for their part to cast doubt on the credibility of the prosecution's star witness, Manafort's former trusted deputy, Rick Gates, who took a deal from the government and turned against his former boss. During his testimony, Gates, 46, acknowledged stealing hundreds of thousands of dollars from Manafort and having an extramarital affair. While Gates and several others indicted by Mueller have pleaded guilty, Manafort refused to cut a deal and insisted on having his day in court. Manafort, who worked on the presidential campaigns of Republicans Gerald Ford, Ronald Reagan, George H.W. Bush and Bob Dole, was Trump's campaign chairman from May to August 2016. He was forced to step down amid questions about his work for Ukraine's former pro-Russian leader Viktor Yanukovych and legal experts say he may be holding out hopes of a pardon from Trump.