And now comes the reckoning for the mainstream news media and the pundits.

After more than two years of intense reporting and endless talking-head speculation about possible collusion between Donald Trump’s presidential campaign and Russian agents in 2016, special counsel Robert S. Mueller III put a huge spike in all of it on Sunday. Attorney General William P. Barr relayed Mr. Mueller’s key findings in a four-page summary of the 22-month investigation: The evidence was insufficient to conclude that Mr. Trump or his associates conspired with Russians to interfere in the campaign.

Mr. Barr’s announcement was a thunderclap to mainstream news outlets and the cadre of mostly liberal-leaning commentators who have spent months emphasizing the possible-collusion narrative in opinion columns and cable TV panel discussions.

“Nobody wants to hear this, but news that Special Prosecutor Robert Mueller is headed home without issuing new charges is a death blow for the reputation of the American news media,” Rolling Stone’s Matt Taibbi wrote in a column published Saturday, a day before Mr. Barr nailed the collusion coffin shut. He added: “Nothing Trump is accused of from now on by the press will be believed by huge chunks of the population.”

Mr. Taibbi wrote that the reporting and commentary asserting collusion between Mr. Trump and Russia belonged in the dustbin of other discarded stories, such as Iraq possessing weapons of mass destruction before the U.S. invasion in 2003. He even called out “Saturday Night Live” — one of Mr. Trump’s favorite Twitter foils — for a cast singalong to Mariah Carey’s “All I Want for Christmas Is You” that featured the line: “Mueller, please come through, because the only option is a coup.”

Journalist and commentator Glenn Greenwald — a longtime skeptic of the collusion angle — tweeted his contempt for the media coverage on Sunday, too: “Check every MSNBC personality, CNN law ‘expert,’ liberal-centrist outlets and #Resistance scam artist and see if you see even an iota of self-reflection, humility or admission of massive error.”

He added: “While standard liberal outlets obediently said whatever they were told by the CIA & FBI, many reporters at right-wing media outlets which are routinely mocked by super-smart liberals as primitive & propagandistic did relentlessly great digging & reporting.”

Mr. Greenwald reserved special vitriol for MSNBC host Rachel Maddow, who he said “went on the air for 2 straight years & fed millions of people conspiratorial garbage & benefited greatly.”

An MSNBC representative declined to comment Sunday; CNN’s representatives did not respond.

Among the theories commentators advanced was one by New York magazine writer Jonathan Chait, who speculated in a cover story in July about whether “the dark crevices of the Russia scandal run not just a little deeper but a lot deeper.” He suggested that “it would be dangerous not to consider the possibility that the [then-upcoming] summit [between Mr. Trump and Russian President Vladimir Putin] is less a negotiation between two heads of state than a meeting between a Russian-intelligence asset and his handler.”

In a statement Sunday night, Mr. Chait stood by his article. “That story relied on reports in credible public sources. None of those reports have been refuted. ... If the full Mueller report does show that media reports on Trump’s ties to Russia were wrong, I would absolutely amend, correct or withdraw commentary I have written on that basis.”

Other news outlets defended their reporting as well, noting that much of it is undisputed and has led to indictments and guilty pleas by figures associated with Mr. Trump’s campaign.

“I’m comfortable with our coverage,” said Dean Baquet, The New York Times’s top editor. “It is never our job to determine illegality, but to expose the actions of people in power. And that’s what we and others have done and will continue to do.”

He noted that Mr. Barr’s letter summarizing Mr. Mueller’s findings points out that the actions that warranted an obstruction inquiry were “the subject of public reporting” — a fact “that’s to the credit of the media.”

In fact, revelations by the Times and The Washington Post about contacts between Russian agents and Mr. Trump’s campaign advisers in 2016 helped prompt the inquiry that the special counsel took over in May 2017. The two newspapers shared a Pulitzer Prize for their reporting on the issue that year.

As Mr. Baquet noted, “On Russia interference, we and others wrote extensively about Russia’s attempt to influence the election, both through hacking and direct approaches by Russians to people around candidate Trump. Those stories were true. And nothing has happened to call into question the reporting about Donald Trump’s financial history, or the use of his charity, or any of the other fine investigative reporting over the past three years.”

“Russiagate” has been a news media obsession since Mr. Trump’s victory in November 2016. The nonpartisan Tyndall Report pegged the total amount of time devoted to the story on the evening newscasts of ABC, CBS and NBC last year at 332 minutes, making it the second-most covered story after the Senate confirmation hearings of Supreme Court Justice Brett M. Kavanaugh. According to a count by the Republican National Committee released Sunday, The Post, the New York Times, CNN.com and MSNBC.com have written a combined 8,507 articles mentioning the special counsel’s investigation.

The cable news networks, particularly CNN and MSNBC, have added hundreds of hours of discussion about the topic, too.

The story undoubtedly was an important factor in shaping voters’ perceptions before the 2018 midterm election, in which Democrats won control of the House.

But the conclusion of the inquiry has put a question once hazily debated into sharp focus: Did the mainstream news media mislead?

“Liberal journalists expected Mueller to build a case for scandalous collusion between the Trump campaign and the Russian government,” said Tim Graham, director of media analysis for the conservative Media Research Center. Noting Mr. Mueller’s broad findings, he said, “So now it’s apparent the news channels merely channeled their wishful thinking. They had a grand denouement in mind, and it didn’t happen. They mocked Trump for saying ‘no collusion,’ and that ended up being the truth. ... The voters should feel punked, swindled.”

Paul Farhi covers the media for The Washington Post.

First Published: March 26, 2019, 4:00 a.m.