Attorney General William Barr refused to testify before the House Judiciary Committee on Thursday, a day after Senate Democrats grilled him over his handling of Special Counsel Robert Mueller's report. Democrats have said they will hold Barr in contempt for his non-appearance, while Republicans claim the ground rules that Chairman Jerry Nadler placed on the hearing were unreasonable.

Trump, who has pledged not to comply with any subpoenas from Congress, remains popular among Republicans, according to recent polls. To date, only one Republican has emerged to challenge the president in 2020: former Massachusetts Gov. Bill Weld.

“I’ve seen this whole movie before … when I worked on the Nixon impeachment,” Weld said, when discussing the aftermath of the Mueller investigation with Jim Braude on Greater Boston Thursday.

In 1974, after the Nixon administration refused to comply with subpoenas from the House Judiciary Committee, the U.S. Supreme Court unanimously ruled against then President Richard Nixon, forcing him to deliver subpoenaed materials over to the courts. Weld believes Nixon’s case showed “that no man is above the law. The president is not above the law.”

But current legal battles may play out differently.

When asked about Barr’s legal explanation for choosing not to bring charges against Trump over obstruction of justice, Weld pointed again to history.

“[Barr] filed this 19-page report with the Justice Department in June of 2018 — unsolicited — and it said no one can commit the offense of obstruction of justice unless they committed the underlying crime. Well, that's completely baseless.

“That would mean that Richard Nixon could not have been proceeded against for contempt of Congress, as he was, unless he had been in the basement of the Watergate Hotel with G. Gordon Liddy and Howard Hunt,” Weld said. “It’s a ridiculous idea.”

Although Weld describes Trump as “a stranger to the truth” and finds ample evidence in the Mueller report to charge Trump with obstructing justice, he does not support impeachment proceedings.

“That's a political conclusion, not a legal conclusion,” he said. Weld noted that impeachment would only bring negative publicity leading up to the 2020 election, which the president might use to his advantage.

The former governor said he is more concerned with Barr’s decision not to indict Trump, and believes that we may be approaching a Constitutional crisis “because the president's strategy, which is now Bill Barr’s strategy, is just to say the other side is partisan.”

“He can't deny that the stuff in Volume II of the Mueller report constitutes obstruction of justice,” Weld said. Weld, who was also an assistant attorney general overseeing the criminal division in the Department of Justice, explained that he would have “sought a sealed indictment.”

The Constitution says a president remains liable to indictment, prosecution and punishment after they leave office, but Weld described that even if Trump were indicted, accountability could be avoided through reelection and by relying on the statute of limitations to lapse over the next five years. A sealed indictment would continue through the statute of limitations.

As U.S. Attorney of Massachusetts in the 1980s, Weld worked with Robert Mueller, whom he called “the straightest man I’ve ever met.”

Asked if Trump would try to stop the special counsel from ever testifying in front of Congress, Weld said that Mueller “might at some point in time, no longer be an employee of the Department of Justice.” Then, with a wink, he noted, “so the position might be a little different then.”

For now, Weld thinks his best chance of defeating Trump starts with winning New Hampshire in the Republican primary, and he also plans to work hard to win Mid-Atlantic and West Coast states.

“I'm here to try to make sure that Mr. Trump does not get six more years of what he's shown this country already,” he said.

This article has been updated.