This post has been updated.

Attorney General William P. Barr’s handling of the Mueller report was already controversial. On Tuesday night, it became a whole lot more controversial.

We knew based upon previous reporting that members of special counsel Robert S. Mueller III’s team were concerned about Barr’s characterization of their report ahead of its release. But now we know Mueller himself shared in the concerns — and spoke up.

The Post’s Devlin Barrett and Matt Zapotosky report that Mueller went so far as to send a letter to the Justice Department after Barr summarized Mueller’s principal conclusions in late March. Mueller took issue with how Barr allowed the report to be portrayed:

At the time Mueller’s letter was sent to Barr on March 27, Barr had days prior announced that Mueller did not find a conspiracy between the Trump campaign and Russian officials seeking to interfere in the 2016 presidential election. In his memo to Congress, Barr also said Mueller had not reached a conclusion about whether Trump had tried to obstruct justice, but that Barr reviewed the evidence and found it insufficient to support such a charge.
Days after Barr’s announcement, Mueller wrote the previously undisclosed private letter to the Justice Department, laying out his concerns in stark terms that shocked senior Justice Department officials, according to people familiar with the discussions.
“The summary letter the Department sent to Congress and released to the public late in the afternoon of March 24 did not fully capture the context, nature, and substance of this office’s work and conclusions,” Mueller wrote. “There is now public confusion about critical aspects of the results of our investigation. This threatens to undermine a central purpose for which the Department appointed the Special Counsel: to assure full public confidence in the outcome of the investigations.”

Given how diplomatic prosecutors and lawyers tend to be, that’s a pretty stunning letter. Mueller’s decision to create a record registering his dismay suggests significant concern -- even as the language may be somewhat muted. (Some have noted the story also says Mueller later told Barr that his letter wasn’t inaccurate. It’s possible to be strictly accurate and also misleading, which is what Mueller seems to believe happened here.)

Mueller’s letter effectively backs up reporting since the Mueller report’s release about how Barr obscured key details and seemed to spin things in a way that favored Trump. Barr initially said that Mueller hadn’t reached a conclusion on obstruction of justice, but he didn’t explain at the time that Mueller had declined to reach such a conclusion regardless of evidence — and because of an existing Justice Department policy saying that you don’t indict a sitting president.

Even amid the blowback against Barr’s initial summary, though, it wasn’t clear that Mueller himself personally disputed it. The two are said to be friends, and while it was reported that members of Mueller’s team privately expressed concern, there was the question of how Mueller himself actually felt.

We now know that he shared in at least some of the major concerns. Mueller’s letter makes clear he doesn’t believe Barr handled the “context” of his report accurately, which lends credence to analysis that Barr skipped over Mueller’s actual justification for not concluding Trump had obstructed justice. In fact, if you look at the Mueller report closely, you’ll see that there are multiple instances in which he indicated there was evidence that President Trump’s conduct satisfied the three key criteria for obstruction.

The 5 crimes Mueller suggests Trump could be charged with

There are also new questions now about whether Barr misled Congress during his March testimony, when he claimed ignorance about how Mueller and his team felt about key aspects of Barr’s letter.

Barr has already been under fire for a number of reasons. During his confirmation hearings, there was his previous commentary arguing that Mueller’s obstruction probe wasn’t warranted and was actually dangerous. Since then, Barr has issued the suspect summary of Mueller’s principal conclusions, borrowed a Trump talking point about the FBI “spying” on his campaign, and then held a news conference before the Mueller report’s release in which he seemed to offer the kind of defense of Trump that you’d expect from one of Trump’s lawyers. Perhaps most importantly of all, he cleared Trump of obstruction even though Mueller seemed to believe it wasn’t the Justice Department’s place to make a decision about it.

The timing of the leaking of Mueller’s letter is certainly conspicuous, given that Barr is set to testify to Congress on Wednesday morning. As with his aides’ comments being leaked, it suggests profound dissatisfaction with Barr’s handling of the matter.

Barr has got a lot of explaining to do.