Three months before Election Day, James Barnes teleconferenced into a strategy meeting about how, exactly, to persuade people not to vote for Donald Trump. The 32-year-old wore his hair loosely gathered in a man bun and had the sober expression of someone who, as a hazard of his occupation, thinks about the president nearly all the time. Other faces popped up on his monitor, offering glimpses into millennial apartments, until someone started a screen share. They were here to review a series of video testimonials by conservatives who had decided to oppose Trump. Barnes and his colleagues wanted to know which ones resonated most with prospective voters on Facebook. Were testimonials from men or women more effective? Midwesterners or Southerners? How many viewers made it past the first 15 seconds?

Barnes, who works at the political nonprofit Acronym, attends these meetings every week. His team has two goals—to nudge voters away from Trump and to close what he politely calls the “enthusiasm gap” for Joe Biden. Using a custom-built tool dubbed Barometer, they micro-­target “movable” voters on Facebook, run randomized tests to see what kind of ads work best, and then adjust them to taste.

Barnes, who spent the early part of his career at Facebook, leads his colleagues in two-week-long “sprints,” following Mark Zuckerberg’s adage about moving fast. In the past year, they’ve completed hundreds of tests, refining their own strategy and sharing insights with other Democratic groups. “We’ve got a larger corpus of data than anyone else about what’s moving ­people,” he says. (One takeaway: Voters love the Midwestern men.)

In 2016, Barnes was the Facebook staffer assigned to get Trump’s digital team comfortable on the platform. Raised in Tennessee, he had been a conservative all his life. As a student at George Washington University, he had chaired the DC Federation of College Republicans, then spent several years as a GOP political consultant. But “working with Trump specifically was not something that I wanted to do,” he says. “There is nothing to like about that man.”

Barnes loved Facebook, though, and he believed in the vision of building a new space for political engagement. He also saw the campaign as a chance to move up in the company’s intensely competitive ranks. And so he pushed through what he describes as “an enormous amount of internal conflict,” reassuring himself that the work was interesting and that he was doing a good job. He showed the campaign, led by an operative named Brad Parscale, how to measure the impact of its ads and fine-tune its messaging strategy, how to expand its reach with the Lookalike Audiences tool, how to use engagement data to hook first-time donors. The result, Facebook executive Andrew Bosworth would later say, was “the single best digital ad campaign I’ve ever seen.”

On the night of the election, before the returns came in, Barnes recalls “thinking that part of my life would be over, because the mission would be accomplished”—his mission as an engineer, that is, not the mission of claiming the White House. Nobody on the team, least of all him, believed Trump would win. Barnes, in fact, had voted for Clinton. The outcome left him rattled. “Now, here it is four years later, and I’m still at it,” he says. “A different chapter of the same book.”

Barnes didn’t leave Facebook until 2019, by which point he’d registered as a Democrat, moved from DC to San Francisco, and cycled through several teams at the company. Then, during his “recharge”—a 30-day vacation perk that Facebook employees receive every five years—he traveled to Peru, drank ayahuasca with a shaman, and found himself on the road to Damascus. When he returned to the States, he quit Facebook and started intermittent fasting. He set to work on a project that would repurpose the strategies he’d learned in 2016 to oppose Trump in 2020.