Late on Tuesday, President Trump tweeted something that’s embarrassing even by his standards: an unfounded conspiracy theory that originated in some of the internet’s worst “fake news” corners.

“Strzok-Page, the incompetent & corrupt FBI lovers, have texts referring to a counter-intelligence operation into the Trump Campaign dating way back to December, 2015,” the president wrote. “SPYGATE is in full force!”

The supposed source for this claim is text messages between two FBI employees, Peter Strzok and Lisa Page, who were having an affair during the 2016 campaign. Their text messages reveal that they were openly hostile to Trump and supportive of Hillary Clinton.

The problem is that, as far as we know, none of those texts mentioned anything about there being a counterintelligence operation against the Trump campaign as early as December 2015. So where the hell did the president come up with that idea?

ThinkProgress’s Judd Legum did some sleuthing and seems to have pieced together the series of events that led to this tweet. It goes roughly like this:

On Monday afternoon, an anonymous Twitter account notes that Page texted Strzok in December 2015 about “oconus lures,” which in FBI parlance means intelligence operations aimed at arresting someone outside the continental United States. The texts do not mention Trump at all, and likely had nothing to do with him, since the FBI’s investigation into Trump didn’t open until July 2016. That didn’t stop the anonymous Twitter user from speculating that this might be “an admission that the FBI wanted to run a baited Sting Op using foreign agents against Trump.” Gateway Pundit, a pro-Trump blog with very low editorial standards but a surprisingly wide readership on the right, picks up the tweet in a Monday article titled “Breaking: Senate releases unredacted texts showing FBI initiated MULTIPLE SPIES in Trump campaign in December 2015.” By Tuesday evening, the story has spread to Fox. At 7:22 pm, Fox Business host Lou Dobbs tweets about the oconus lures texts. At 8:37 pm on Tuesday, Trump sends his tweet about the conspiracy theory. About an hour later, Fox News host Laura Ingraham says on air that “when you read those texts, it certainly looks like they [the FBI] were trying to put more lures into the campaign in December 2015.” Republican Rep. Ron DeSantis, one of her panelists, agrees with Ingraham’s interpretation, saying that it is now “clear” that the FBI investigation into Trump started earlier than July 2016.

So what happened, it seems, is that a conspiratorial interpretation of texts between two FBI employees, one entirely unfounded in the actual evidence, got laundered from the fringe right-wing media to the right-wing mainstream through Fox News personalities — and eventually reached up to a member of Congress and the president of the United States.

This says something profound about the way the country is broken today — about how Trump and the conservative media have combined forces to warp the way millions of Americans understand the world around them.

Trump has turned the conservative media into a massive conspiracy machine

It’s worth noting that the entire “Spygate” controversy Trump is hyping — the idea that the FBI put a spy in the Trump campaign — is grounded in a lie. There is no evidence that the FBI implanted an operative into the Trump campaign; every attempt to gin up support for this notion has been roundly debunked.

The thin basis in reality is the actions of a retired university professor in Britain named Stefan Halper. Halper, an American who taught for years at Cambridge University in the UK, has been outed in the press as a secret FBI “informant” who met with several Trump campaign advisers in mid-2016 at the bureau’s behest.

The goal of these meetings was allegedly to assess whether there were any real links between the Trump campaign and Russia, enough to fuel a wider investigation. This isn’t the same thing as a spy being in Trump’s campaign, obviously, since Halper never actually worked for him — nor is there evidence that Halper went beyond the bounds of a legitimate counterintelligence investigation into Russian election meddling.

The best way to analyze “Spygate” is not as a partisan dispute, but rather a conspiracy theory. It is not a legitimate ideological disagreement so much as a ginned-up controversy Trump has capitalized on to justify his argument that the FBI is hopelessly biased against him.

The Associated Press reported last month that Trump came up with the term “spy” as part of a branding campaign; the president, the AP reported, believed the “nefarious term would resonate more in the media and with the public.”

The entire “Spygate” controversy is not a debate between two rational sides, but rather a fight between the truth and a pro-Trump camp looking for evidence that can be spun to justify the president’s narrative. The mere fact that the president is championing “Spygate” means that Republicans at all levels, from Congress to Fox News to the rank-and-file voters, are more likely to believe in it.

“Misinformation is much more likely to stick when it conforms with people’s preexisting beliefs, especially those connected to social groups that they’re a part of,” says Kevin Arceneaux, a political scientist at Temple University. “In politics, that plays out (usually) through partisanship: Republicans are much more likely to believe false information that confirms their worldview, and Democrats are likely to do the opposite.”

“Any evidence against the theory is reinterpreted as evidence for it”

This means that there’s every incentive for Republican-aligned media outlets to hype stories that seem to confirm the president’s narrative, like the “oconus lures” text. Journalistic standards, in theory, are supposed to keep a lid on this kind of behavior — journalists shouldn’t disseminate information they can’t confirm. But pro-Trump sites like Gateway Pundit don’t adhere to these standards, and Fox News seems to have no qualms about citing such dubious sources of information.

Since the president watches Fox, this risks generating a profoundly vicious cycle. Fox picks up on some random internet rumor, the president picks it up from Fox, and then Fox and other right-wing outlets leap to defend what the president tweeted, which only reinforces Trump’s sense that he’s right.

Between the conservative media and the president, Republican voters end up with an entirely skewed picture of reality — one in which the FBI has been plotting against Trump since December 2015.

The worst part is that it’s not at all clear how to stop this. Research shows that once conspiracy theories are embedded in people’s minds, they’re nearly impossible to dislodge.

“A known aspect of conspiracy theorizing is that the cognition involved is ‘self-sealing,’ such that any evidence against the theory is reinterpreted as evidence for it,” Stephan Lewandowsky, a psychologist at the University of Bristol who studies conspiracy theories, tells Vox. He continues:

For example, if scientists are accused of creating a “hoax” such as climate change, but they are then exonerated by multiple enquiries, then a conspiracy theorist will not accept that as evidence of their innocence but as evidence of a broad conspiracy (to create a world government or whatever) that involves the government, judiciary, Soros, and anyone else who once shared a supermarket checkout line with Al Gore in the 1970s.

Because it’s nigh impossible to dislodge these ideas once entrenched, Lewandowsky says, the best way to stop them is to prevent them from spreading. “It’s much more important to protect the public at large from being drawn into the vortex of conspiracy theories than it is to try and change the mind of the committed few,” he says.

The problem, though, is that the most powerful and famous man in the world is the vortex. When it comes to “Spygate,” he has sucked one of America’s two major political parties down with him.

Jane Coaston contributed reporting to this piece.