Todd Heisler/The New York Times
WASHINGTON — Robert S. Mueller III revealed the scope of a historic Russian campaign to sabotage the 2016 presidential election in a much-anticipated report made public on Thursday, and he detailed a frantic monthslong effort by President Trump to thwart a federal investigation that imperiled his presidency from the start.
Mr. Mueller, the special counsel, laid out how his team of prosecutors wrestled with whether Mr. Trump’s actions added up to a criminal obstruction-of-justice offense. They ultimately chose not to charge Mr. Trump, citing numerous legal and factual constraints, but pointedly declined to exonerate him and suggested that it might be the role of Congress to settle the matter.
The report laid bare that Mr. Trump was elected with the help of a foreign power, and cataloged numerous meetings between Mr. Trump’s advisers and Russians seeking to influence the campaign and the presidential transition team — encounters set up in pursuit of business deals, policy initiatives and political dirt about Hillary Clinton, the Democratic candidate for president.
The special counsel concluded that there was “insufficient evidence” to determine that the president or his aides had engaged in a criminal conspiracy with the Russians, even though the Trump campaign welcomed the Kremlin sabotage effort and “expected it would benefit electorally” from the hacks and leaks of Democratic emails.
Then, after federal investigators opened an inquiry into the extraordinary Russian campaign, the president repeatedly tried to undermine it.
“If we had confidence after a thorough investigation of the facts that the president clearly did not commit obstruction of justice, we would so state,” Mr. Mueller’s investigators wrote. “Based on the facts and the applicable legal standards, however, we are unable to reach that judgment.”
Fevered speculation, now put to rest, arose in some circles that Mr. Trump and his immediate family might be in legal peril from Mr. Mueller’s investigation. At the same time, the report offered reams of evidence of a climate of deceit — and a base impulse for self-preservation — among a president and his top aides not seen since the days of Richard M. Nixon.
That impulse prompted some presidential advisers to try to block Mr. Trump’s demands that they take steps to protect him from federal investigators. Some feared getting wrapped up in the widening inquiry.
“The president’s efforts to influence the investigation were mostly unsuccessful, but that is largely because the persons who surrounded the president declined to carry out orders or accede to his requests,” the report said.
The special counsel found that Mr. Trump had the authority to make many of his most controversial decisions, including the firing of James B. Comey as the F.B.I. director, by virtue of the powers the Constitution grants him. At the same time, it is a far more damning portrayal of his behavior than the one presented last month in a four-page letter released by Attorney General William P. Barr.
“The incidents were often carried out through one-on-one meetings in which the president sought to use his official power outside of usual channels,” the report said. “These actions ranged from efforts to remove the special counsel and to reverse the effect of the attorney general’s recusal; to the attempted use of official power to limit the scope of the investigation; to direct and indirect contacts with witnesses with the potential to influence their testimony. Viewing the acts collectively can help to illuminate their significance.”
In his letter, Mr. Barr announced that while Mr. Mueller had made no judgment about whether Mr. Trump had obstructed justice, he had stepped in to decide that the president had not.
Mr. Barr defended his decision in a news conference on Thursday and said that some of the president’s actions were understandable given the “context” of his situation.
“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,” Mr. Barr said.
The Mueller report is a sometimes gripping account of a presidency consumed by a sprawling investigation, and of a president seized by paranoia about what it might unearth.
Immediately after learning that a special counsel had been appointed to lead the Russia investigation, the report said, Mr. Trump became distraught and slumped in his chair.
“Oh, my God. This is terrible,” he said. “This is the end of my presidency. I’m fucked.”
Mr. Trump had long denounced the inquiry as a politically motivated “witch hunt.” But since it began, a half-dozen former Trump aides have been indicted or convicted of crimes, most of them for lying to Congress or federal investigators.