The billionaire Tesla CEO has turned his personal feed into a non-stop pro-Trump megaphone, sharing MAGA talking points to his roughly 203 million followers on X. It’s a remarkable level of reach by any influencer standards (Taylor Swift has 95 million X followers, and 283 million on the much larger Instagram).

Because the X platform is owned and operated by Musk, the tech mogul’s political musings and commentary (which can number 20 or more a day) have effectively become a built-in feature of the service. For many users, Musk’s tweets feel inescapable — seeming to pop up whether the person knows or cares about Musk, his companies, politics, or even business in general.

They’re not imagining it.

Fortune conducted a multi-day experiment to gauge just how prevalent Musk really is on his social media platform. In approximately 90% of the sessions on X that Fortune conducted — through a dozen different test accounts — a post from Musk appeared at least once in the timeline, usually much more often.

None of the X accounts that Fortune created for the experiment followed Musk or actively engaged with his content. And yet within two sessions, all 12 of the test accounts had been exposed to Musk’s tweets in X’s algorithmically-powered “For You” feed.

The results seem to corroborate reports that Musk has continued to put his thumb on the algorithmic scale to amplify his own tweets, and they add important new details that show how the world’s richest person has managed to procure a popular communications platform and refashion it into a personal tool to influence public opinion. A spokesman for X did not respond to emails and texts seeking comment.

Among the Musk tweets that appeared in Fortune’s test account feeds was one falsely claiming “The Dems have imported massive numbers of illegals to swing states” in order to create “a one-party, deep blue socialist state.” There were several Musk posts promoting Trump’s appearance on Joe Rogan’s podcast, as well as a recent rally in New York during which Musk spoke. Musk shared several anti-Harris advertisements, including one funded by Musk’s pro-Trump political action committee that refers to the Vice President using misogynistic vulgarities.

Political content, whether authored by Musk or other users, accounted for significant portions — in one case 83% — of the tweets that appeared in the feeds of the test accounts.

Even clicking “not interested in Elon Musk” (an option users could at one time select for all celebrities on Twitter but which now appears to be available only with respect to Musk and a handful of others) did not exorcize Musk from the feed. In fact, after one Fortune test account clicked the option to declare itself apathetic towards the tech billionaire, posts from Musk more than doubled.

A force feeding of Musk content

According to two former Twitter employees, there is effectively “no chance” that the algorithmic “For You” feed is organically pulling in so much content from one person or on one topic, even if Musk is the most followed person on the platform. The algorithm was designed to “be as neutral as possible,” and to pull content for a user based on their selected interests and location, unless and until the user engaged with enough content to steer their recommendation algorithm toward a wider array of content, one of the people explained.

The other former employee noted that, in order to get so much of the same content in front of users, it’s almost certain that “a manual override” is occurring, injecting Musk and political content into the “For You” recommendation algorithm regardless of a user’s interests. 

Musk, who acquired Twitter in 2022 for $44 billion and renamed it X, has set about radically revamping the service, firing thousands of workers, closing offices, and bringing back scores of extreme accounts that had been banned. He said the changes, including the near elimination of content moderation teams working to keep user feeds free of offensive posts, was in order to bring “free speech” to a platform he claimed had been controlled by activist employees, the government and advertisers

In 2023, Musk reportedly fired an engineer who told him that user views on his tweets were declining. An 80-person team was tasked with getting to the bottom of the issue and fixing it, the Verge reported. The result was apparently a code change that ensured Musk’s tweets would not get flagged by the filters that typically sort tweets for different users of the service according to their interests.

The impact of Musk’s recent barrage of political tweets on voters is difficult to quantify. Social media is a powerful tool that advertisers spend heavily on to earn consumer mindshare.

According to media reports, Musk’s pro-Trump America Pac spent millions of dollars to advertise on Facebook and Instagram in the months leading up to the election, but only 4% of its social media ad spending on ads that ran on X. While the data was interpreted by some as a sign of the X platform’s weakness, it could simply suggest that Musk’s Pac has no need to spend money on the platform given his ability to reach users for free.

A steady increase in Musk content

To conduct the experiment, Fortune created 12 test accounts of users with different profiles, with interests ranging from fashion and beauty, to business and finance to sports. For five consecutive days in late October, Fortune conducted separate sessions on X with each of the 12 accounts. 

Each account session lasted five minutes and passed by between roughly 60 to 100 posts each time. During two-thirds of the total sessions, Musk was among the first three posts that appeared at the top of a user’s feed, and the billionaire was by far the single most common individual account seen across all of the feeds.

While eight of the 12 accounts showed no posts from Musk on the first day of usage, his posts appeared each subsequent day, and with increased frequency, despite the absence of engagement with Musk content, Fortune found. 

An account with selected interests of travel, careers and science went from being served two posts by Musk in a single session, to 22 posts by Musk in a later session. Nearly all of the accounts, regardless of what they selected as topics of interest, experienced a similar trajectory, going from just a few Musk posts to many, sometimes dozens.

While Musk tweets about a variety of topics, including SpaceX, Tesla, and his other various businesses, Republican party rhetoric has become a mainstay. One Musk recent tweet that appeared in Fortune’s test accounts featured a meme purportedly criticizing a lack of voter identification requirements, despite most states requiring identification to vote in-person. And another of a meme regarding inflation, arguing its higher than President Joe Biden claims using a picture of Hunter Biden.  

Across all of the accounts, day after day, politics was clearly the main subject, and overwhelmingly in-line with Musk’s own political views. Political content made up anywhere from 19% to 83% of the “For You” feed on the different accounts, despite 10 of the 12 accounts engaging with no such content. Of that political content, between 55% and 82% of it was obviously pro-Trump or obviously anti-Harris, Fortune’s analysis found. Out of roughly 4,500 X posts that Fortune logged, just 46 were obviously pro-Harris.  

Will the political content on X ebb after the election? It’s possible, though Musk seems unlikely to stop using X to promote his personal interests. 

And there’s little anyone inside or outside the company can do to stop it. 

“If you’re ready to get fired, that’s when you say no,” a current X employee said regarding Musk’s frequent and varying demands. The billionaire’s mantra for his employees, including those at X, is “critical, excellent and loyal.”

Are you an X employee or someone with insight or a tip to share? Contact Kali Hays securely through Signal at +1-949-280-0267 or at kali.hays@fortune.com