WASHINGTON — The investigation led by Robert Mueller found no evidence that President Trump or any of his aides coordinated with the Russian government’s 2016 election interference, according to a summary of the special counsel’s key findings made public Sunday by Attorney General William Barr.

Mueller, who spent nearly two years investigating Moscow’s determined effort to sabotage the last presidential election, found no conspiracy “despite multiple offers from Russian-affiliated individuals to assist the Trump campaign,’’ Barr wrote in a letter to lawmakers.

Mueller’s team drew no conclusions about whether Trump illegally obstructed justice, Barr said, so he made his own decision. The attorney general and his deputy, Rod Rosenstein, determined that the special counsel’s investigators had insufficient evidence to establish that the president committed that offense.

He cautioned, however, that Mueller’s report states that “while this report does not conclude that the president committed a crime, it also does not exonerate him’’ on the obstruction of justice issue.

The president trumpeted the news almost immediately, even as he mischaracterized the special counsel’s findings. “It was a complete and total exoneration,’’ Trump told reporters in Florida before boarding Air Force One. “It’s a shame that our country had to go through this. To be honest, it’s a shame that your president has had to go through this.’’

He added, “This was an illegal takedown that failed.’’

For Trump, it was a deeply satisfying end to one of the most fraught weekends of his presidency. Like everyone else, he had been forced to wait while Barr and a small circle of officials at the Justice Department in Washington pored over Mueller’s report and decided what to make public.

Trump’s remarks, aides said, were an early taste of how he is likely to react to his new political reality. He plans to attend a rally in Grand Rapids, Mich., on Thursday evening, which will give him a platform to go on the offensive.

Mueller, who has been a spectral presence in the capital for nearly two years — so often discussed, but so rarely seen — was photographed leaving a church on Sunday morning just across Lafayette Square from the White House.

Hours later, Barr delivered his letter describing the findings to Congress. But congressional Democrats have demanded more, and the letter could be just the beginning of a lengthy constitutional battle between Congress and the Justice Department about whether Mueller’s full report will be made public. Democrats have also called for the attorney general to turn over all of the special counsel’s investigative files.

Barr’s letter said that his “goal and intent’’ was to release as much of the Mueller report as possible but warned that some of the report was based on grand jury material that “by law cannot be made public.’’ Barr planned at a later date to send lawmakers the detailed summary of Mueller’s full report that the attorney general is required under law to deliver to Capitol Hill.

Lawmakers on Sunday also criticized Barr’s conclusion that the president had not obstructed justice — which requires making a determination about whether Trump had “corrupt intent’’ when he took steps to impede the investigation at different turns — when the special counsel’s team never questioned the president in person. After months of debate over a potential interview, Mueller’s investigators agreed to accept written answers from the president.

Barr’s letter said that the Mueller report identified no actions that, in his and Rosenstein’s minds, “constitute obstructive conduct, had a nexus to a pending or contemplated proceeding, and were done with corrupt intent.’’ Barr did not consult Mueller in writing his letter to leaders of the congressional judiciary committees, a Justice Department official said Sunday.

Shortly after the release of the Mueller findings, Democratic Representative Jerrold Nadler of New York, chairman of the House Judiciary Committee, said on Twitter that he planned to call Barr to testify about what he said were “very concerning discrepancies and final decision-making at the Justice Department.’’

The Russia investigation has buffeted the White House from the earliest days of the Trump administration, with many current and former aides to Trump brought for questioning to the special counsel’s warren of offices in a plain building in downtown Washington. FBI agents fanned out across the nation and traveled to numerous countries. Members of Mueller’s team questioned some witnesses at airports after they landed in the United States.

Ultimately, a half-dozen former Trump aides were indicted or convicted of crimes, most for conspiracy or lying to investigators. Twenty-five Russian intelligence operatives and experts in social media manipulation were charged in 2018 in two extraordinarily detailed indictments released by the special counsel. The inquiry concluded without charging any Americans for conspiring with the Russian campaign.

To prove a conspiracy, former prosecutors said, Mueller’s team would have had to show that Trump or one or more of his associates agreed that Russia should interfere in the election through computer espionage, illegal use of social media, or other criminal means.

Campaign officials at times were eager to accept benefits from Russia’s covert operation. “I love it,’’ Donald Trump Jr., the president’s eldest son, responded when an intermediary said a Russian emissary wanted to give the campaign damaging information at a Trump Tower meeting in June 2016.

Trump himself urged Russia to try to unearth deleted e-mails from a private server Clinton had used when she was secretary of state.

And Roger Stone, the president’s longtime friend, tried to enlist intermediaries to connect with WikiLeaks, Russia’s chosen depository for Democratic e-mails stolen by Russian hackers. But absent an agreement with the Russian government to break the law, former Justice Department officials said, none of that made Trump or his associates co-conspirators with the Kremlin.

“There is a big difference between saying, ‘Gosh, I think WikiLeaks has the ability to hack into the Democratic National Committee computers,’ and saying, ‘We would like them to dump those out in the public, so let’s call them up and ask them to do that,’’’ said Mary McCord, a former top-ranking national security official at the Justice Department.

Mueller was given a wide mandate — to investigate not only Russian election interference but also “any matters that may arise directly from that investigation.’’ Mueller has farmed out multiple aspects of his inquiry to several US attorneys’ offices, and those investigations continue.

Barr’s letter said that the special counsel’s office employed 19 lawyers and was assisted by about 40 FBI agents, intelligence analysts, forensic accountants and other staff. About 500 witnesses were interviewed, and 13 foreign governments were asked to turn over evidence.

Overall, the special counsel’s office issued more than 2,800 subpoenas, executed nearly 500 search warrants, and obtained more than 230 orders for communications records.

Mueller will not recommend new indictments, ending speculation that he might charge some of Trump’s aides in the future. The Justice Department’s general practice is not to identify the targets of its investigations if prosecutors decide not to bring charges, so as not to tarnish their reputations. Rosenstein emphasized this point in a speech.

“It’s important,’’ he said, “for government officials to refrain from making allegations of wrongdoing when they’re not backed by charges that we are prepared to prove in court.’’