WASHINGTON — To thwart a federal investigation of Russian efforts to help him win the White House, President Donald Trump fired the FBI director, ordered an aide to fire special counsel Robert Mueller and urged associates to pressure the attorney general to curb the inquiry.

From the first months of his administration, Trump pushed repeatedly to limit the inquiry into Russian interference with the 2016 election that began with the FBI and continued under Mueller. His attempts to block or curb the inquiry that he worried could tarnish his presidency are detailed in Mueller's final report on his 22-month investigation, released Thursday by the Justice Department.

Four months into his term, Trump fired FBI Director James Comey. The next day he told Russia's foreign minister that he "faced great pressure because of Russia. That's taken off.... I'm not under investigation."

When Mueller was appointed days later to take over that investigation, Trump feared it would end his presidency. He told then-White House counsel Don McGahn to fire Mueller, but McGahn refused and later told another White House aide that the president asked him to "do crazy s---."

Trump also erupted at his first attorney general, Jeff Sessions, for removing himself from managing the Russia investigation because of his work for Trump's campaign. After Mueller was appointed in May 2017, Sessions handed Trump a resignation letter, but Trump pocketed it instead of ousting him. Then-Chief of Staff Reince Priebus said it would be bad for Trump to keep the letter because it would act like a "shock collar" that would hold "DOJ by the throat."

Trump met in June 2017 with former campaign manager Corey Lewandowski and forced him to take dictation for a message to Sessions. Trump said he felt "treated very unfairly" and told Sessions that the inquiry should be limited to "investigating election meddling for future elections," not the one that had put him in office. Lewandowski never delivered the message.

None of those was sufficient for prosecutors to conclude that Trump had committed a crime by obstructing the Russia investigation, in part because his aides largely refused to carry out his orders. But Mueller's office pointedly declined to say that it had cleared the president of wrongdoing, writing instead that the report "also does not exonerate him."

"The president's efforts to influence the investigation were mostly unsuccessful, but that was largely because the persons who surrounded the president declined to carry out orders or accede to his requests," the report said. "Consistent with that pattern, the evidence we obtained would not support potential obstruction of justice charges against the president's aides and associates beyond those already filed."

Trump's personal lawyers said in a statement Thursday that the president's actions were justified. They said he acted correctly in firing Comey for launching a "biased, political attack," though that is not the reason Trump gave at the time for ousting the FBI director.

"Instead of protecting the time-honored principle that the president – as with any American – is innocent until proven guilty, they clearly set up a scheme to derail the President – pushing a twisted narrative claiming he was guilty until proven innocent," they said in the statement.

Mueller also suggested Congress could make its own judgment about the president's conduct with evidence from the report, one that is not necessarily tethered to criminal law.

"With respect to whether the president can be found to have obstructed justice by exercising his powers under Article II of the Constitution, we concluded that Congress has authority to prohibit a president's corrupt use of his authority in order to protect the integrity of the administration of justice," Mueller's report said.

The chairman of the House Judiciary Committee, Rep. Jerry Nadler, D-N.Y., said the report provided substantial evidence that Trump tried to obstruct justice.

“Even in its incomplete form, the Mueller report outlines disturbing evidence that President Trump engaged in obstruction of justice and other misconduct," Nadler said. “The report concluded there was ‘substantial evidence’ that President Trump attempted to prevent an investigation into his campaign and his own conduct."

More about Justice Department special counsel Robert Mueller's report:

Mueller report documents links between Trump campaign and Russia, steps to thwart probe; finds no conspiracy

Mueller report: Trump's anger over Russia probe may have saved him from obstruction charge

Donald Trump reacts to Mueller report: 'It’s called no collusion, no obstruction'

The redacted report was released in two volumes on Thursday, one dedicated to answering whether the Trump campaign conspired with Russia to interfere in the 2016 election and the other to whether the president attempted to obstruct the investigation.

In the report, Mueller laid out what investigators considered to be key events in which they believed Trump had sought to influence the investigation into his campaign. Most had been revealed publicly already, but the special counsel's report spelled them out in staggering detail.

Among the evidence outlined in the report:

Trump’s reaction to the Russia investigation. Sessions announced his recusal from the investigation March 2, 2017, because he had worked on Trump's campaign. Trump expressed anger, and that weekend Trump took Sessions aside and urged him to "unrecuse."

Trump fired Comey on May 9, 2017. Trump had earlier asked Comey to go easy on his investigation of then-National Security Adviser Mike Flynn. On March 30, Trump asked Comey to "lift the cloud" of the Russia investigation. The day after firing him, Trump told Russia's foreign minister: "I just fired the head of the FBI. He was crazy, a real nut job."

The appointment of Mueller and efforts to remove him. Trump reacted angrily to Mueller’s appointment. "Oh my God," Trump said, according to the report. "This is terrible. This is the end of my presidency."

Efforts to have McGahn deny that Trump ordered him to have Mueller removed. After the media reported on June 14, 2017, that Mueller was investigating possible obstruction, Trump reacted with a series of tweets criticizing the Justice Department and Mueller. Trump called White House counsel Don McGahn at home June 17, 2017, and said Mueller had conflicts and should be removed. McGahn didn’t carry out the direction, however, deciding that he would resign rather than trigger what he regarded as a potential Saturday Night Massacre, a reference to former President Richard Nixon firing prosecutors during the Watergate investigation. Trump later met with McGahn in the Oval Office and pressured him again, but McGahn refused to back away. McGahn “perceived the president to be testing his mettle,” the report said.

Efforts to curtail Mueller’s investigation. Trump met June 19, 2017, in the Oval Office with Lewandowski, his former campaign manager, and dictated the message to Sessions. Lewandowski said he understood. A month later, Trump met with Lewandowski again and the former aide said the message would be delivered soon. Hours later, Trump criticized Sessions in an interview with The New York Times. Lewandowski didn’t deliver the message but asked White House official Rick Dearborn to do it. But the request "definitely raised an eyebrow" for Dearborn, who was uncomfortable with the task and didn’t follow through.

Conduct involving former Comey and former National Security Adviser Mike Flynn. Flynn falsely denied in mid-January to FBI agents and top administration officials that he had talked to Russian Ambassador Sergey Kislyak. On Feb. 14, the day after Trump requested Flynn’s resignation, Trump told an outside adviser: “Now that we fired Flynn, the Russia thing is over.” The adviser disagreed. Later that afternoon, Trump met one-on-one with Comey and said, “I hope you can see your way clear to letting this go, to letting Flynn go. He is a good guy. I hope you can let this go.” Former Deputy National Security Advisor K.T. McFarland declined a Trump request to draft a letter stating Trump hadn’t directed Flynn to discuss sanctions with Kislyak because she wasn’t sure it was true. A White House counsel’s office attorney thought the request would look like a quid pro quo for an ambassadorship she was offered.

Efforts to prevent public disclosure of evidence. When Trump heard of press inquiries about a June 9, 2016, meeting in Trump Tower between a Russian lawyer and members of his campaign, the president edited a press statement for his son Donald Trump Jr., who attended the meeting, by deleting a line that acknowledged the meeting was with "an individual who (Trump Jr.) was told might have information helpful to the campaign" and instead said only the meeting was about adoptions.

The president's communications director, Hope Hicks, had warned Trump that email setting up the meeting were "really bad" and the story would be "massive" when it broke. Trump told Hicks on at least three occasions not to disclose information about the meeting. "But the evidence does not establish that the president took steps to prevent the emails or other information about the June 9 meeting from being provided to Congress or the special counsel," Mueller's report said.

Further efforts to have Sessions take control of the investigation. Trump met privately with Sessions in the Oval Office in October 2017 and told him to "take (a) look" at investigating Clinton. After Flynn pleaded guilty in December 2017, Trump met with Sessions in the Oval Office and suggested if he un-recused himself, he would be viewed a "hero." "I’m not going to do anything or direct you to do anything," Trump told Sessions, according to a note-taker. "I just want to be treated fairly." Sessions said he had never seen anything improper during the campaign, but didn’t change his decision.

Conduct toward Flynn and former campaign chairman Paul Manafort to influence their testimony. In November 2017, the report says that the president’s personal counsel left a voicemail with Flynn’s counsel saying the White House needed a “heads up” about Flynn’s testimony and cooperation with the government. “The president also privately asked advisers to pass messages to Flynn conveying that the president still cared about him and encouraging him to stay strong," Mueller's report said. In January 2018, Manafort told Gates he had talked to the president’s personal counsel and they were “going to take care of us.”

The reports says Gates asked Manafort if anyone mentioned pardons, and Manafort said no one used that word. Some of the material was redacted due to ongoing prosecutions. When Flynn ended his joint defense agreement with Trump, the president’s personal counsel said he would make sure Trump knew of his "hostility." But Trump praised Manafort publicly during his trial and said he was being treated unfairly.

Conduct involving former personal lawyer Michael Cohen. After the FBI raided the home and office of former Trump lawyer Michael Cohen, Trump reached out to Cohen publicly and privately to "hang in there" and "stay strong." Trump lawyer Rudy Giuliani set up a "back channel" through another lawyer, Robert Costello, who told Cohen he should "Sleep well tonight ... you have friends in high places." Cohen told Mueller that he understood that as long as he stayed on message, Trump would take care of him – either with a pardon or by shutting the investigation down. But Trump called Cohen a “rat” after he began cooperating with Mueller during the summer of 2018.

Mueller said he relied on several factors in weighing potential obstruction charges, including whether there was an act of obstruction, a connection to an official proceeding and criminal or corrupt intent. Such prosecutorial decisions are often reached without interviewing an investigation’s subject, as Trump declined to be interviewed in this case, Mueller wrote.

"The evidence we obtained about the president’s actions and intent presents difficult issues that would need to be resolved if we were making a traditional prosecutorial judgment," Mueller's report said. “At the same time, 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. Based on the facts and the applicable legal standards, we are unable to reach that judgment. Accordingly, while this report does not conclude that the president committed a crime, it also does not exonerate him."

Because Mueller made no decision on obstruction charges, Attorney General William Barr and Deputy Attorney General Rod Rosenstein, who appointed Mueller and oversaw much of his work, made their own judgment that the evidence the special counsel gathered “is not sufficient to establish that the president committed an obstruction-of-justice offense.”

“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 said Thursday.

Trump’s personal lawyer argued that the president couldn’t be charged with obstruction for using his constitutional authority to close an investigation or terminate an FBI director. While acknowledging that broad authority, Mueller said his authority coexists with Congress’s to enact laws that protect investigations.

Mueller secured several guilty pleas during his investigation, which could be viewed as obstruction by those participants.

Flynn pleaded guilty to lying to FBI agents about interactions with Russians ambassador Sergey Kislyak before Trump took office. during the transition. Flynn awaits sentencing. But the question legal experts have asked is why he lied to investigators four days after taking office – and whether someone told him to lie.

Cohen pleaded guilty to lying to Congress about the extent of negotiations during the 2016 election year for a real-estate deal in Moscow. Cohen later testified at a House hearing that Trump had told him indirectly to lie, which the president denied.

Mueller's report found that "while there is evidence, described below, that the president knew Cohen provided false testimony to Congress about the Trump Tower Moscow project, the evidence available to us does not establish that the president directed or aided Cohen's false testimony."

But the report said Trump appeared to have tried to influence Cohen's testimony. "In analyzing the president's intent in his actions towards Cohen as a potential witness, there is evidence that could support the inference that the president intended to

discourage Cohen from cooperating with the government because Cohen's information would shed adverse light on the President's campaign-period conduct and statements," Mueller's report said.

Contributing: John Kelly, Ledyard King, Gregory Korte, Kevin McCoy, Steve Reilly and Deirdre Shesgreen

More about special counsel Robert Mueller's report:

Mueller report: Investigation found no evidence Trump conspired with Russia, leaves obstruction question open

Trump claims 'total exoneration' from Mueller summary despite lack of answers on obstruction

Mueller report: Criminal investigation moves to political realm as Barr summarizes for Congress