Some members of special counsel Robert Mueller's team have expressed frustration that Attorney General William Barr cleared President Trump of obstruction of justice, and they believe the evidence that Trump sought to impede the investigation is stronger than Barr suggested in his March letter summarizing Mueller's findings, a U.S. official who has spoken with them tells NBC News.

Justice Department officials say Barr had no choice but to render a judgment, because the special counsel regulations say that he is ultimately in charge of the investigation. If Mueller believed Trump was guilty of obstruction, he could have said so, the officials argue — but he didn't do that in his report.

Three government officials have told NBC News that a dispute within the special counsel's office on the facts and the law was one factor behind Mueller's decision not to make a call on the obstruction question.

The New York Times and Washington Post first reported that some members of the Mueller team were upset with how Barr portrayed the evidence.

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