On several occasions, Attorney General William P. Barr has been assertive. The investigation led by special counsel Robert S. Mueller III, he declared in a four-page letter March 24, didn’t find that President Trump’s 2016 campaign coordinated with Russia’s efforts to influence that election. What’s more, he and Deputy Attorney General Rod J. Rosenstein had looked at Mueller’s report and determined that Trump hadn’t provably violated obstruction of justice statutes.

In a news conference April 18, shortly before the report was made public, Barr was more adamant: There was no collusion between Trump’s team and Russia, and not only was there not criminal obstruction, but also the anger displayed by Trump that could be interpreted as obstruction was warranted, given the frustrating circumstances Trump faced.

Barr has stepped forward as the seemingly objective face of the case Trump has been making since May 2017: that Trump did nothing wrong. But Barr’s ability to play that role effectively has eroded over time, both with the revelation that Mueller took issue with his March 24 letter and, Wednesday, under questioning about the report by Democrats on the Senate Judiciary Committee.

Over the course of that questioning, Barr admitted he hadn’t reviewed the evidence underlying Mueller’s findings on obstruction, he hadn’t looked at the evidence undergirding the origination of the probe into possible coordination and, at one point, even made a comment raising questions about his familiarity with one of the key issues at the heart of the probe.

It was Sen. Kamala D. Harris (D-Calif.) who drew the most significant blood.

“The special counsel’s investigation produced a great deal of evidence,” she said. “I’m led to believe it included witnesses’ notes and emails, witnesses’ congressional testimony, witnesses’ interviews which were summarized in the FBI 302 forms, former FBI director [James B. ] Comey’s memos and the president’s public statements.

“My question is,” she continued, “in reaching your conclusion, did you personally review all of the underlying evidence?”

“No, we took — we accepted — ” Barr said.

“Did Mr. Rosenstein?” Harris interjected.

“We accepted the statements in the report as the factual record,” Barr said. “We did not go underneath it to see whether or not they were accurate, we accepted it as accurate. It made our — ”

“So you accepted the report as the evidence?” Harris asked. Yes, Barr replied.

“You did not question or look at the underlying evidence that supports the conclusions in the report?” she asked. No, he said, nor did Rosenstein, to his knowledge.

Harris appeared to marvel at his response.

“Yet you represented to the American public that the evidence was not, quote, ‘sufficient to support an obstruction of justice offense,’ ” she said.

“The evidence in the report,” Barr said.

A short while later, that lack of familiarity with the underlying evidence became important during questioning by Sen. Richard J. Durbin (D-Ill.).

Durbin outlined the evidence that was already known to the FBI in July 2016 when it opened a counterintelligence investigation into possible coordination between Trump’s campaign and Russia. That Russia had hacked the Democratic National Committee. That a Trump aide named George Papadopoulos had been informed in April that Russia had incriminating emails on Clinton. That the aide in May told an Australian diplomat named Alexander Downer. And that, in late July, material stolen from the DNC was dumped by WikiLeaks. (It was this dump that prompted Australia to inform the FBI about Papadopoulos’s earlier comments.)

“Do you believe that it was an appropriate predicate,” Durbin asked, “for opening a counterintelligence investigation to determine whether Russia had targeted people on the Trump campaign to offer hacked information that might impact the presidential election?”

Barr said: “I’d have to see exactly what the report was from Downer, the Australian, Downer, and exactly what he quoted Papadopoulos as saying. But from what you just read, I’m not sure what the correlation was between the Russians having dirt and jumping to the conclusion that that suggested foreknowledge of the hacking.”

By itself, that’s a remarkable admission: that Barr wasn’t familiar with what precisely Downer had said about the tip that kicked off the entire probe. But it also undercut an earlier exchange Barr had with Sen. Lindsey O. Graham (R-S.C.), the chairman of the committee, who had worked at the outset to build a protective scaffolding around Trump by suggesting nefarious behavior on the part of Democrats and the Obama administration.

“Do you share my concerns about the counterintelligence investigation,” Graham said, hoping to raise questions about the validity of the probe overall, “how it was opened and why it was opened?”

“Yes,” Barr replied — though his concerns about the origin of the investigation didn’t extend so far as to read what Downer had said about what Papadopoulos told him.

Shortly before Harris questioned Barr, Sen. Cory Booker (D-N.J.) had an opportunity to do so. He focused on what he described as Barr’s willingness to brush off as unimportant activity that may have been legal but which, in Booker’s eyes, was at least morally questionable.

“In our country, we know it is illegal for a campaign and wrong for a campaign to share polling data with an American super PAC,” Booker said, “but we have here, documented, a level of coordination with a foreign adversary sharing polling data, and we seem to be, and your conduct seems to be, trying to normalize that behavior.”

It’s true that a campaign can’t share polling information with a political action committee that’s running independent expenditures on its behalf. What Booker was referring to was a number of occasions in which Paul Manafort — at the time Trump’s campaign chairman — had shared polling data from the campaign with his colleague Konstantin Kilimnik, a Ukrainian believed by the FBI to be linked to Russian intelligence.

“We right now have a new normal in our country,” Booker said later. “We have a document that shows over 200 connections between a presidential campaign and a foreign adversary. Sharing information that would be illegal if you shared it with a super PAC, we know that.”

“What information was shared?” Barr asked.

“Polling data was shared, sir,” Booker replied. “It’s in the report; I can cite you the page.”

“With who?” Barr responded.

Booker continued with his questioning.

The polling data issue wasn’t just an incidental event. One attorney on Mueller’s team told a federal judge this year that the sharing of that data got “very much to the heart of what the special counsel’s office is investigating.”

Why? Well, it’s a Trump campaign staffer deliberately offering proprietary information to someone that is probably linked to Russia’s intelligence service — which was at the time actively trying to interfere in the election. Manafort probably knew about Kilimnik’s ties; while he denied to Mueller’s team that Kilimnik was linked to the government, his deputy, Rick Gates, said he suspected that Kilimnik was a spy, an opinion he had shared with Manafort.

It’s probable (but not certain) that Barr wasn’t unfamiliar with the exchange but, instead, trying to make a point to Booker. That it’s not clear whether Kilimnik then passed the information to the Russian government is important. If Manafort was sharing poll data with a colleague to, say, use as leverage with former business partners to make a buck, that’s not something that gets at the heart of what Mueller was looking at.

But even if that were the direction in which Barr was headed, it’s a problematic case to make. Mueller was pointed in noting in the report that questions about the purpose of sharing the data remains unclear.

"Because of questions about Manafort’s credibility and our limited ability to gather evidence on what happened to the polling data after it was sent to Kilimnik,” the report states, “the Office could not assess what Kilimnik (or others he may have given it to) did with it.”

This is an important subtext to everything that Barr has said about the report. On a number of points, Mueller wasn’t able to answer the questions he was asked, for a variety of reasons. (Including, we’ll note, that his only contact with Trump himself was written questions that mostly elicited answers of “I don’t recall.”)

That bit of nuance never made it into Barr’s descriptions of Mueller’s work. Nor, we learned Wednesday, did Barr at any point try to dive any deeper than what Mueller laid on his desk.