Shortly after he took over as White House chief of staff in late July 2017, John F. Kelly imposed a new process for vetting the information that got to President Trump.

“The new system, laid out in two memos co-authored by Kelly and [then-staff secretary Rob] Porter and distributed to Cabinet members and White House staffers in recent days,” Politico reported at the time, “is designed to ensure that the president won’t see any external policy documents, internal policy memos, agency reports and even news articles that haven’t been vetted. Kelly’s deputy, Kirstjen Nielsen, is also expected to assume an integral role.”

Instead of random articles from conservative news outlets, Kelly wanted Trump to see vetted, specialized information that would guide the president's thinking.

There had already been an example of Trump seizing on questionable reporting to the detriment of the White House. In March 2017, Trump accused his predecessor, Barack Obama, of having ordered a wiretap of Trump Tower, a claim he made after reading a Breitbart article that cited analysis by radio host Mark Levin. Neither Levin nor the Breitbart piece claimed that Trump Tower was wiretapped, but they did say that “the Obama administration sought, and eventually obtained, authorization to eavesdrop on the Trump campaign” — a claim that Trump may have interpreted to mean wiretapping. It’s not true, anyway; investigators with the FBI obtained a Foreign Intelligence Surveillance Act warrant to surveil Trump adviser Carter Page after he left the 2016 Trump campaign.

Kelly’s rule was meant to avoid similar problems, to avoid an apparently common practice in which advisers and allies slipped articles to Trump intended to turn his attention to various issues. Over time, though, Trump wore down Kelly’s ability to filter out misleading information. Kelly left the administration, as did Porter and Nielsen. There’s little indication at this point that Trump’s media diet is anything other than a buffet of conservative television and Internet articles.

That diet might just have contributed to the most significant threat Trump's presidency has seen.

A whistleblower complaint made public Thursday morning alleges that Trump sought to influence the government of Ukraine to dig into allegations about impropriety involving former vice president Joe Biden — a leading contender to face Trump in next year’s presidential election. The allegations involve a number of reported conversations focused on Ukraine and actions by Rudolph W. Giuliani, Trump’s personal attorney, training attention on Ukraine. But they also include a significant number of news articles published by a popular conservative opinion columnist for the Hill — articles that the whistleblower seems to think contributed to the fervency of the Trump-Giuliani effort.

Some Ukrainian politics are worth noting at the outset. At the beginning of this year, Ukraine was in the midst of a presidential election campaign. Incumbent Petro Poroshenko faced a crowded field of challengers, including Volodymyr Zelensky, the eventual winner. One member of Poroshenko’s administration was his prosecutor general, Yuri Lutsenko. As the March 31 primary approached, Poroshenko trailed Zelensky and in some polls was at risk of not making the runoff. Zelensky said that if he won, he would replace Lutsenko.

By that point, the whistleblower complaint suggests, Giuliani was already sniffing around, trying to dig up dirt on Biden. Giuliani had met with former Ukrainian prosecutor general Viktor Shokin in late 2018, an official whom Biden had pressured Ukraine to fire. Giuliani came to believe that Biden did so to block an investigation by Shokin into a company that had Biden’s son Hunter as one of its board members. This has been shown to be untrue, but Giuliani to this day insists otherwise.

In January and February, the complaint alleges, Giuliani and Lutsenko — who replaced Shokin — met. At the time, Giuliani was fervently (and occasionally unhelpfully) defending Trump as the president navigated the investigation by then-special counsel Robert S. Mueller III. It’s safe to assume that Giuliani and Trump were in regular communication and, therefore, that Trump may have been privy to Giuliani’s conversations with the Ukrainian officials.

The Biden allegations were still largely beneath the surface at that point. But in March and early April, they came to the attention of John Solomon, a columnist at the Hill. Solomon had been an investigative reporter for the outlet but in May 2018 was transitioned to the opinion team after complaints from his peers about his thoroughness.

Solomon interviewed Lutsenko in late March, shortly before the Ukrainian election, in which Lutsenko’s job was at risk. In that interview, Lutsenko made a number of significant claims. He claimed that he’d been provided with a list of people not to prosecute by the United States’ then-ambassador to Ukraine, Marie Yovanovitch. He said he was opening an investigation into a member of parliament who during the 2016 campaign publicized allegations of secret payments to Trump’s then-campaign chairman, Paul Manafort. And he claimed that he was investigating Biden’s push to oust Shokin.

All of those allegations were published by Solomon in late March and early April. Trump himself tweeted out a reference to the allegation about the member of parliament, Serhiy Leshchenko. As of writing, the article about Biden has been shared more than 37,000 times. Solomon further amplified the stories by appearing on Fox News (including on Mark Levin’s show on the network), where he was very likely to be seen by Trump.

The only problem? Lutsenko eventually backtracked on his assertions. He reversed his allegation about Yovanovitch in mid-April, shortly before Zelensky easily won election. He told Bloomberg News a month later that there was no evidence of wrongdoing by the Bidens — a claim he reiterated to The Washington Post this week. That member of parliament targeted by Lutsenko, Leshchenko, was cleared by a Ukrainian court in mid-July.

Solomon also reported other explosive allegations targeting Biden and other Trump opponents. An article from early May that has been shared more than 73,000 times focuses on how a Democratic National Committee staffer had solicited information from the Ukrainian Embassy in 2016 — implying again that Ukraine had tried to interfere in the election. Solomon quoted extensively from a former embassy staffer named Andrii Telizhenko — someone who the whistleblower claims was an ally of Lutsenko and who’d met with Giuliani later that month. (The Post’s fact-checkers have evaluated claims about the DNC research effort.)

The day prior, the New York Times had picked up the Biden-Shokin story, giving it newfound attention.

The whistleblower suggests that the Lutsenko allegations highlighted by Solomon’s reporting drove policy in the White House. Yovanovitch was ousted from her position in early May. In his call with Zelensky in late July, Trump disparaged her as “bad news, and the people she was dealing with in the Ukraine were bad news.” The whistleblower alleges to have been told that any meeting between Zelensky and Trump “would depend on whether Zelensky showed willingness to ‘play ball’ on the issues that had been publicly aired” — via Solomon — “by Mr. Lutsenko and Mr. Giuliani.”

Trump himself had elevated stories featured by Solomon, both on Twitter and by mentioning them in interviews. Trump mentioned the allegations of interference to Fox News’s Sean Hannity in late April and the following month mentioned the Biden story in another Fox News interview.

There’s an unclear line here between Trump and Giuliani and the public reporting by Solomon that’s a focus of the whistleblower’s complaint. Was Solomon lifting up claims by Lutsenko that were then seized upon by Trump and Giuliani? Did Giuliani point Solomon to Lutsenko in the first place? Were Lutsenko’s eventually retracted assertions linked to the political situation in Ukraine?

What’s clear, though, is that Solomon’s reporting and the stories he helped advance simultaneously were politically useful to Trump and potentially influenced his thinking. These reports about what had happened in Ukraine were precisely the sort of outside, unvetted information that Kelly once tried to keep off Trump’s desk. Kelly left the White House in late 2018 — right before Giuliani started digging around in Ukraine.

Last week, as questions about Trump and Ukraine were heating up, another change in employment was announced. Solomon is leaving the Hill to start his own media outlet.