Washington — Reiterating that special counsel Robert Mueller found no evidence of President Trump's 2016 campaign colluding with Russia, Attorney General William Barr mounted a vigorous defense of Mr. Trump's actions in a preemptive press conference ahead of the release of a redacted version of Mueller's report, saying the president faced "an unprecedented situation" throughout the two-year investigation.

"As he entered into office, and sought to perform his responsibilities as President, federal agents and prosecutors were scrutinizing his conduct before and after taking office, and the conduct of some of his associates," Barr said at a Thursday morning press conference.

Standing alongside Deputy Attorney General Rod Rosenstein, the attorney general said Mr. Trump held a "sincere belief" that Mueller's investigation was hindering his ability to perform his duties as commander-in-chief.

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"As the special counsel's report acknowledges, there is substantial evidence to show that the president was frustrated and angered by a sincere belief that the investigation was undermining his presidency, propelled by his political opponents and fueled by illegal leaks," Barr added.

Asked by CBS News' White House correspondent Paula Reid about his recognition of the president's emotions and claims by Democrats that he is acting as a spokesperson for the White House, the attorney general defended his statements and said his characterization of the Mueller report as "unprecedented" is warranted.

CBS News' Paula Reid to AG Barr: "Here, you have remarks that are quite generous to the president, including acknowledging his feelings and his emotions. What do you say to people on both sides of the aisle that you are trying to protect the president?" https://t.co/2AcTw6G473 pic.twitter.com/Mri15UAf8A — CBS Evening News (@CBSEveningNews) April 18, 2019

"The statements about his beliefs, his sincere beliefs, are recognized in the report that there was substantial evidence for that," Barr added, referring to Mr. Trump. "So I'm not sure what your basis is for saying that I'm generous to the president."

Attorney General William Barr speaks alongside Deputy Attorney General Rod Rosenstein, right, about the release of a redacted version of special counsel Robert Mueller's report during a news conference, Thursday, April 18, 2019, at the Department of Justice in Washington. Patrick Semansky / AP

In the press conference, Barr said the the White House "fully cooperated" with Mueller's probe and provided "unfettered access" to documents and testimony by senior administration officials. He added the president opted not to invoke executive privilege on any material on the redacted Mueller report when the Justice Department shared a copy with the White House on March 29.

"The president confirmed that, in the interests of transparency and full disclosure to the American people, he would not assert privilege over the special counsel's report," Barr said.

In his nearly two-year investigation, Mueller probed whether the Trump campaign coordinated with the Russian government in Moscow's sophisticated campaign to meddle in the 2016 election, as well as possible obstruction of justice offenses committed by the president while in office.

In what the White House claimed as a "total and complete exoneration" of Mr. Trump, Barr wrote in a four-page letter in March that Mueller did not find Trump campaign associates had "conspired or coordinated" with the Kremlin during the 2016 campaign.

In his summary, Barr said he and Rosenstein also determined, without considering a longstanding Justice Department opinion stating sitting presidents cannot be indicted, that Mueller's findings were not "sufficient" to prove Mr. Trump committed obstruction of justice. Still, the attorney general said Mueller stopped short of exonerating the president of obstructing justice. "While this report does not conclude that the President committed a crime, it also does not exonerate him," Mueller wrote in his report, according to Barr's summary.

On Thursday, Barr strongly reiterated the Mueller probe found no evidence of any type of coordination between American citizens, including the president and his campaign officials, and the Russian government with the objective to interfere with the 2016 election.

"That is the bottom line," Barr said.