Jack Posobiec is the bureau chief and sole employee of the Washington, D.C., office of the Rebel, a Canadian media outlet that specializes in far-right video commentary. Last weekend, I met him at a Peet’s Coffee a few blocks from the White House. He told me, “As a journalist, I use all the tools at my disposal”—mostly YouTube, Periscope, and Twitter—“to seek the truth and disseminate the truth. That’s the purpose of journalism, right? At the same time, I also do what I call 4-D journalism, meaning that I’m willing to break the fourth wall. I’m willing to walk into an anti-Trump march and start chanting anti-Clinton stuff—to make something happen, and then cover what happens. So, activism tactics mixed with traditional journalism tactics.”

When he was a student at Temple University, he said, he double-majored in political science and broadcast journalism. He joined the Navy, and was stationed in Asia for five years; when he returned to the United States, he worked as a Trump campaign volunteer before joining the Rebel. “Last week, I called my mom and went, ‘Hey, Ma, look who’s actually using his college degree!’ ” Now, in the final hours of the French Presidential contest between Emmanuel Macron, a centrist who supports the European Union, and Marine Le Pen, a far-right, anti-immigrant nationalist, Posobiec’s “4-D journalism” might have a serious impact.

I reached Posobiec by phone on Saturday. The previous day, he told me, he had flown from Washington to Miami, to attend a party hosted by the far-right self-promoter Milo Yiannopoulos. Posobiec spent much of Friday monitoring /pol/, the 4chan message board, which has recently become a breeding ground for nationalist trolls, both in the U.S. and abroad. “People were claiming something big was coming, so I just kept hitting refresh,” he told me. Shortly before 3 P.M., an anonymous 4chan user posted nine gigabytes of information—purportedly hacked e-mails, photographs, and internal documents from the campaign of Emmanuel Macron. Posobiec could not know whether all the information was authentic—he didn’t even have time to glance through most of the thousands of pages—but he considered it his journalistic duty to let his followers know about the leak. “Massive doc dump at /pol/,” he tweeted. He included a link to the 4chan post, along with a hashtag: #MacronLeaks.

This was retweeted a few hundred times, but then the hashtag seemed to stagnate. “I know my Twitter engagement rate very well, and, to be honest, I thought it was pretty low,” he said. “I figured, Oh, well, it’s a Friday afternoon. Maybe this isn’t going to take off. Besides, nobody knew what was in the documents, so it was possible that people looked at one and went, ‘O.K., this is a budget spreadsheet,’ and got bored.” Posobiec is anti-globalist, and he had long hoped that Le Pen, who wants France to leave the euro and the European Union, would win the election. He sent out a few more tweets with the #MacronLeaks hashtag, then went to the rented mansion where the party, Cinco de Milo, was being held. Yiannopoulos made his grand entrance, descending a curving staircase with a large yellow snake around his neck. Around midnight, Posobiec checked his phone, which had been charging in another room. #MacronLeaks was trending in France, and there was a banner headline about it on the Drudge Report. The Macron campaign issued a statement claiming that the people who hacked his e-mail had mixed authentic documents with fake ones, in order to “sow doubt.”

On his phone, Posobiec started a live video on Periscope, which he called “Press Conference on #MacronLeaks.” The first few minutes consisted of Posobiec and his girlfriend dancing to “Bad and Boujee,” by Migos, while Posobiec occasionally made the “O.K.” hand gesture. “Vive la France,” he said, after a while. “The truth is a powerful thing.”

The French election commission prohibits the publication, within two days before an election, of any information that might distort the election’s results. As Reuters points out, though, the commission “may find it difficult to enforce its rules in an era where people get much of their news online, information flows freely across borders and many users are anonymous.” According to a forensic analysis by the Digital Forensic Research Lab, Posobiec’s Twitter feed was the second most powerful amplifier of the #MacronLeaks hashtag, after Wikileaks, which also tweeted a link to the documents. This analysis also implied that Posobiec—or his confederates, perhaps Russian trolls—had used bots to promote the story artificially. “I wouldn’t know how to use a bot,” Posobiec told me. “I just find interesting things and post them to my Twitter feed. Look, journalists have gotten so bad that if they see someone like me doing real work, actually digging through documents and distributing them to the people, they assume there must be some sort of conspiracy behind it. I hope that, if anything, this can be a learning experience for the New York Times and Le Monde and all the rest of them, to understand how real journalism works.”