Attorney General William Barr says he disagreed with former special counsel Robert Mueller's decision not to determine whether President Donald Trump had broken the law by obstructing his probe into Russian interference in the 2016 election.

"I personally felt he could’ve reached a decision," Barr told CBS News in an interview that aired Thursday, disagreeing with Mueller's stance that he could not because of Department of Justice guidelines against indicting a sitting president.

NEW: Attorney General Barr tells @JanCBS he “personally felt” Special Counsel Robert Mueller “could've reached a decision” on obstruction of justice by President Trump.



More on @CBSEveningNews tonight and @CBSThisMorning Friday. #CTM pic.twitter.com/b8ik2q32ZK — CBS This Morning (@CBSThisMorning) May 30, 2019

In his first public comments on his two-year investigation into Trump and Russia, Mueller said Wednesday he didn't weigh whether the president should be indicted because he knew he could not be. His report laid out evidence that Trump had tried to interfere with the probe, and Barr and then-Deputy Attorney Rod Rosenstein determined it didn't warrant criminal charges.

"The opinion says you cannot indict a president while he’s in office, but he could’ve reached a decision as to whether it was criminal activity," Barr said. "But he had his reasons for not doing it, which he explained. And I’m not going to, you know, argue about those reasons. But when he didn’t make a decision, the Deputy Attorney General Rod Rosenstein and I felt it was necessary for us, as the heads of the department, to reach that decision."

Asked about what some have interpreted as Mueller's interest in having Congress tackle's Trump conduct — the ex-special counsel noted on Wednesday that "the Constitution requires a process other than the criminal justice system to formally accuse a sitting president of wrongdoing" — Barr disagreed again.

"Well, I’m not sure what he was suggesting, but you know, the Department of Justice doesn't use our powers of investigating crimes as an adjunct to Congress," Barr told CBS.