For nearly two years, conservative operatives have been trying to weaponize the Ukraine-based story that has led Trump to the brink of impeachment. A look back over the coverage of the story—a repeatedly discredited conspiracy theory involving Joe Biden and his son Hunter’s work in Ukraine—suggests that America’s news organizations continue to be just as susceptible to manipulation by political partisans pushing complicated and hard-to-check foreign narratives as they were in 2016. In fact, several of the same players are involved. “There’s no effective mechanism in this country for weeding disinformation out,” Paul Barrett, the deputy director of N.Y.U.’s Stern Center for Business and Human Rights, and the author of the recent study “Disinformation and the 2020 Election,” said. “We’re not doing anything about it at all.”

Anyone trying to track the Ukrainian conspiracy stories that were eventually embraced by President Trump is likely to get mired in the same echo chamber of right-wing news purveyors that misinformed voters in 2016. A pivotal source of the allegations against the Bidens, for instance, is the Government Accountability Institute, a Florida-based opposition-research operation that was founded by the former Trump political adviser Stephen Bannon—the same conservative nonprofit that ginned up questionable stories about the Clintons during the last Presidential campaign. In both instances, much of the coverage of the scandal was kicked off by Peter Schweizer, a longtime conservative political writer who is an editor-at-large at Breitbart News and the president of the Government Accountability Institute. Since its founding, in 2012, the group has largely been funded with millions of dollars in tax-exempt donations from the family foundation of the New York hedge-fund magnate Robert Mercer, who was a major donor to Trump’s 2016 campaign. In the organization’s most recently available I.R.S. tax filings, for 2017, Mercer’s daughter Rebekah is listed as the board chairman.

Asked about the Government Accountability Institute’s role in this year’s Biden scandal coverage, Bannon e-mailed to say, “It’s key. It was the predicate,” as it had been for much of the previous Clinton scandal coverage. As Joshua Green describes in “Devil’s Bargain,” his book, from 2017, about Bannon’s role in the Trump campaign, Bannon designed the organization as a means of transmitting partisan dirt-digging to the mainstream media. He realized that, though mainstream reporters were suspicious of partisan opinion, they were open to damning facts about public figures, regardless of the sourcing. He set out, with Schweizer, to produce material that would generate mainstream coverage, and right-wing outrage.

Thus, during the last Presidential campaign, under the auspices of the Government Accountability Institute, Schweizer published the best-selling book “Clinton Cash.” In a novel arrangement, he doled out negative scoops about the Clintons from it in advance to a variety of mainstream news outlets, including the Times. The paper disclosed its arrangement with the book’s author to its readers, and maintained that it independently verified and expanded on the information. But when it ran a front-page story derived from the book on April 24, 2015, the Times stirred controversy and criticism, including from its own public editor.

The story insinuated that, as Secretary of State, Hillary Clinton had risked national security by facilitating the sale of American uranium mines to Russia in exchange for more than two million dollars in contributions to the Clinton Foundation from the businessmen behind the deal, who worked for a company called Uranium One. The story enabled Clinton’s opponents to frame her as greedy and corrupt. Even a year after she had lost the race, the Fox News host Sean Hannity was still invoking it on air, calling it “the biggest scandal ever involving Russia.”

Yet later reporting poked holes in the story’s insinuation of corruption, and argued that the amount of uranium involved was insignificant. (Schweizer didn’t respond to phone calls from The New Yorker.) On Thursday, the Daily Beast identified what it said were over a dozen passages in his book, “Secret Empires: How the American Political Class Hides Corruption and Enriches Family and Friends,” that were lifted from other sources, such as Wikipedia—a charge that his publisher, HarperCollins, denied amounted to a violation of fair use.

For those who recall the “Clinton Cash” controversy, the baseless tales claiming that Biden corruptly intervened on behalf of his son’s Ukrainian business interests feel a lot like the movie “Groundhog Day.” In March of 2018, Schweizer and the Government Accountability Institute once again produced a book that was perfectly timed for the Presidential campaign. “Secret Empires” devoted a chapter to the subject of “Bidens in Ukraine,” which laid out the conflicts of interest posed by the wheeling and dealing of Biden’s son Hunter. (An additional chapter laid out Hunter Biden’s business deals in China.) As the book recounted, in 2014, Hunter Biden, a Washington lobbyist, took a profitable post on the board of Burisma, a Ukrainian gas company run by a shady oligarch, while his father, who was then the Vice-President, handled a drive to rid Ukraine of corruption. Other news organizations, including the Times and the Wall Street Journal, had already run stories on the same unethical-seeming morass. (In July, The New Yorker published a piece about the relationship between Joe and Hunter Biden that dismissed allegations of any illegality in the Ukraine matter but included some concerns from Obama Administration officials that Hunter could potentially undermine his father’s work.)

But Schweizer went a step further. His chapter implied not just that Burisma was a crooked company but that the end of a Ukrainian criminal investigation into it on January 12, 2017, was in some unstated way connected to Joe Biden’s visit to the country four days later. In this way, Schweizer floated the possibility that, as Vice-President, Biden had abused his power to protect the company or his son from prosecution. Yet Schweizer provided no proof of causation nor evidence of illegality.

As he rolled out his new book, Schweizer promoted it in all the usual conservative news outlets, including “Hannity” and “The Story with Martha MacCallum,” on Fox News. But the turning point in the Biden coverage, it appears, was in late 2018, when Trump’s private lawyer and political advocate, the former New York City mayor Rudy Giuliani, got involved. That winter, Giuliani began speaking to current and former Ukrainian officials about the Biden conspiracy theory, and meeting with them repeatedly in New York and Europe. Among those officials was Viktor Shokin, a former top Ukrainian prosecutor who was sacked in March, 2016, after European and U.S. officials, including Joe Biden, complained that he was lax in curbing corruption. Shokin claimed that he had lost his powerful post not because of his poor performance but rather because Biden wanted to stop his investigation of Burisma, in order to protect his son. The facts didn’t back this up. The Burisma investigation had been dormant under Shokin. But in March, according to NBC News, Giuliani gave the Secretary of State, Mike Pompeo, a packet of Trump Hotel folders containing the purported evidence against Biden, including Giuliani’s interview with Shokin and his strategy to spread the Biden story, “including segments being placed on Fox News.” Before long, this explosive, politically useful legend took on a life of its own in America’s conservative media.

As an anonymous whistle-blower’s complaint to Congress revealed, and as the Washington Post has reported, no journalist played a bigger part in fuelling the Biden corruption narrative than John Solomon, who until last week was an opinion columnist and executive vice-president of The Hill, in Washington. Solomon had been a respected investigative reporter for the Washington Post, but in recent years he worked for overtly conservative outlets, including a stint as the editor of the Washington Times. As Giuliani conspired this past spring with questionable Ukrainian sources, Solomon pumped out a string of eye-catching stories echoing those sources’ claims about the Bidens. This appears to have been no coincidence. According to NBC, the Giuliani documents show that Solomon’s columns were part of the Trump team’s strategy. (The New Yorker was unable to reach John Solomon, and a question e-mailed to the editor of The Hill, about whether the publication stood by Solomon’s stories, went unanswered.)

This spring, Solomon wrote a series of columns, based on an interview with Ukraine’s top prosecutor, Yuriy Lutsenko. On March 26th, Solomon wrote a column about Lutsenko’s claim that the then U.S. Ambassador to Ukraine, an Obama holdover named Marie Yovanovitch, had given him a list of politically protected figures that he was forbidden from prosecuting—a charge the State Department dismissed as “an outright fabrication.” That same day, Solomon wrote another column suggesting a new investigation into Clinton, which he shared in a tweet, writing, “Did Ukraine try to secretly help Hillary Clinton win the 2016 election? Chief prosecutor says there’s enough evidence to start investigating.”

On April 1st, Solomon turned his focus to Biden, writing a column for The Hill called “Joe Biden’s 2020 Ukrainian Nightmare,” which claimed that Ukraine was reopening its criminal probe into Burisma. It also repeated the unsubstantiated claim that Shokin’s investigation into the company had been cut short at the behest of Biden.

In Solomon’s April 1st column, he cited Schweizer’s book. Two days later, Schweizer sent “kudos” to Solomon during an interview on Breitbart News, and added, “We’re talking about potentially legal jeopardy involving the Vice-President’s family.” Schweizer opined that it was “all the sort of thing that needs to be investigated and looked into by a grand jury,” and added, “it’s pretty clear that you have a pattern that the for-sale sign was open with the Biden family . . . and that in itself demands investigation in the United States.”

Soon, both Schweizer and Solomon were appearing repeatedly on Fox News, spreading the anti-Biden narrative further. According to the liberal watchdog group Media Matters, during the month of April, Fox ran at least twelve segments about Solomon’s reporting on Biden. After one of seven episodes in which Sean Hannity discussed it on his show, President Trump tweeted a reference to Solomon’s reporting. His son Donald Trump, Jr., took up the narrative, too, and tweeted a link to a story in the Daily Wire, a conservative outlet, which echoed Solomon’s claims.

On April 7th, Giuliani appeared on Fox and demanded that the Justice Department investigate the Democrats’ Ukraine dealings. On April 25th, the same day that Joe Biden officially declared that he was running for President, Trump himself called in to Hannity’s show on Fox, saying that he wanted the Attorney General, Bill Barr, to be involved. By raising the spectre of a criminal investigation, Trump, a President dogged by allegations of corruption had, with the help of the conservative echo chamber, managed to cast his chief political rival in a parallel story, leaving the public in a fog of suspicion and confusion. As Barrett, of N.Y.U., explained it, “The consequence is that we begin to inch our way towards the mire that Russians are in where ordinary people lose their ability to tell truth from untruth, and even cease caring about it.”

By May, the mainstream media, including the Times, had picked up on the story about Biden and Ukraine. Although the Times’ piece ran under a headline pointing out that the scandal was being “promoted by Trump and Allies,” and, midway, noted that there was no evidence of criminality, critics attacked the paper for reprising the Uranium One playbook. “It’s precisely what we saw in the last election,” Yochai Benkler, a professor at Harvard Law School and the co-author of the recent book “Network Propaganda: Manipulation, Disinformation, and Radicalization in American Politics,” told me. Benkler argues that when a publication with the Times’ credibility pays any attention to a fringe conspiracy theory, it “provides enormous validation” just by covering the story. “I don’t fault the Times for doing a story,” he said. “But it’s not like the nineteen-sixties anymore, when there were just three TV networks. You live in a country where a large part of the population is susceptible to propaganda. There’s a new editorial responsibility to be much more careful and not bury the denial.”

By mid-summer, the Times and other mainstream outlets, most notably Bloomberg News, had more or less knocked down the conspiracy theories. By then, Trump was so invested in the counterfactual narrative that he was demanding that Ukraine’s new President provide confirmation of it, as the whistle-blower’s complaint relates. Or, as documents released by Congress earlier this week revealing discussions between his emissaries to Ukraine put it, “Potus really wants the deliverable.” With Trump facing the prospect of impeachment in the House of Representatives, it appears that he is a casualty of his side’s own disinformation. “Whether Trump and Giuliani are dupes of their own propaganda I can’t say. But the timeline is completely consistent with that,” Benkler said. “Either way, it proves that running an Administration based on Hannity is dangerous.”

A previous version of this piece mischaracterized the New York Times’ engagement with Peter Schweizer, and one element of its reporting on Uranium One.