The N.F.L. is a natural cauldron of our culture wars. The league is the most conservative, Republican, and nationalistic of the major American sports associations. More than 83 percent of N.F.L. fans are white, according to a Reuters report citing a 2007 study, and fans are 20 percent more likely to be Republicans than Democrats. Nearly 70 percent of the players, meanwhile, are black, according to data from the Institute for Diversity and Ethics in Sport. N.F.L. owners, with a few exceptions, lean Republican; several of them donated to Donald Trump’s campaign, and some donated $1 million apiece to his inauguration committee. Colin Kaepernick, who led the 49ers to the Super Bowl in 2013, was a mixed-race quarterback who had, at first quietly, insisted on beginning each game by taking a knee during the national anthem. Kaepernick’s status off the field as a protestor grew, it so happened, as his play declined. He lost his starting position to the sub-mediocre Blaine Gabbert, and then went on to become the most conspicuous backup quarterback in N.F.L. history.

Kaepernick was joined in his protests by about a dozen other players around the league, who would either take knees or raise their fists during the anthem. He was photographed kneeling for the cover of Time magazine (“The Perilous Fight”), drew a slew of death threats, and was called all sorts of bad things in the press by anonymous owners and league executives. (“I don’t want him anywhere near my team,” one front-office executive told Bleacher Report’s Mike Freeman. “He’s a traitor.”) Kaepernick was also blamed for a hiccup in the N.F.L.’s TV ratings during 2016—about an 11 percent drop over the first half of the season—though the saturation coverage of the presidential election was cited as a bigger factor.

Neither saga was mutually exclusive; Kaepernick and football, Trump and Hillary Clinton all occupied distinct corners in the seething cultural combat zone. Football had become its own sprawling mess of a cause célèbre, another battleground in the culture wars that seemed to be breaking out everywhere. The game is “the last bastion of hope for toughness in America in men,” said University of Michigan coach Jim Harbaugh (John’s brother), defending football to HBO’s Andrea Kremer, and it was only a matter of seconds before someone looked askance. Studio host Bryant Gumbel called the quote “not exactly a quote for the Age of Enlightenment,” which set off Rush Limbaugh in the predictable direction. (“Gumbel epitomizes the modern-day cultural left.”) Whether or not they represent a silent majority, a vocal and substantial population today will dismiss any criticism of football as an elitist affront to their selfhood. “People that say, ‘I won’t let my son play [football]’ are fools,” former Arizona coach Bruce Arians told venerable N.F.L. reporter Peter King. “We have this fear of concussion—that is real—but not all of those . . . statistics can prove anything.”

The coach’s words carry a whiff of persecution. Not just of the sport, but of the ethic and culture that has grown around it—something conservative and essential to American traditions. “This makes football akin to the Confederate flag, or Christmas decorations in public spaces, or taxpayer-supported art depicting Jesus in a tank of urine,” wrote Chuck Klosterman in his essay “Sudden Death (Over Time).” Football, he continued, “becomes intractable precisely because so many people want to see it eliminated.”

Trump’s campaign was predicated on many of the cultural, generational, and demographic tensions that football had incubated for years. His criticism boiled down to a familiar refrain: football had become over-regulated and sissified. Football’s biggest critics, it seemed, were the same bubble-world liberals in the media, ivory-tower scientists (who overplay the dangers of concussions), and soft coastal suits who never played the game—and never met a Trump voter. It was only a matter of time before Trump served up Kaepernick, the vegan quarterback, as red meat to his base.

Kaepernick was a Trumpian villain straight out of central casting—big ’fro, swarthy skin, and a San Francisco jersey. If Kaepernick did not exist, some ingenious Russian troll-bot would invent him. “The N.F.L. is way down in their ratings,” Trump taunted the league at a campaign rally in Greeley, Colorado, a week before the election. He said that politics was “a much rougher game than football,” and also more exciting. “We’ve taken a lot of people away from the N.F.L.,” Trump boasted. “And the other reason”— he paused—“is Kaepernick! Kaepernick!” Cries of displeasure, cued: “Booooo!” “Traitor!” “U.S.A., U.S.A.!” Trump had mentioned Kaepernick before, after he first started kneeling. “Maybe he should find a country that works better for him,” Trump said of Kaepernick to a conservative radio host in Seattle. “Let him try. It won’t happen.” It was only a matter of time before Trump-style politics crashed into the N.F.L. coliseum.

Allegiance to sports team and political tribe had become two of our culture’s strongest identity markers. You hear the word “fan” used interchangeably with “diehard”—as in “faith dies hard.” Trump’s business model was predicated on drawing faith from willing fans at the expense of easy foils. Winning itself was the highest imperative he could offer. There was no call to the broader American community, its diversity, or better angles—just the notion that he himself is a winner. America no longer won, so Trump—he alone—was what the country needed. His pitch was akin to a team hiring a new coach, because he had “won everywhere he’s ever been.” As with any good salesman, Trump could tell a simple story. His story was that our government was occupied by a corrupt political “establishment”; we had neglected our borders, indulged political correctness, and made our country less than great. To Trump, the N.F.L. represented its own kind of establishment. It was an issue that was personal to him, as someone who had tried and failed for decades to join its ranks. It, too, was stagnant, increasingly delicate, and over-tolerant of political correctness, as Kaepernick embodied. The N.F.L. was reality TV, like Trump; it operated on a star system, as Trump’s campaign did (himself). Insomuch as politics had referees—the mainstream media, rules of decorum, ethical norms—they were ripe for flouting and abuse. Trump tipped politics onto a level of unregulated personal fouls. Who knew where the story would lead and who would win? That’s the reality-TV part, and the Master Don of the genre dominated the campaign. Winning is everything, isn’t it? And the crowd went nuts in both directions as another loser—the scrawny Kaepernick in this case, playing for the 2–14 2016 49ers—was carted off, never (as of this writing) to play a down in the N.F.L. again.

Kaepernick photographed alongside his teammate Chris Harper during a game against the Los Angeles Rams on December 24, 2016.

By Michael Zagaris/San Francisco 49ers/Getty Images.

As it happened, a few months after I wrote a profile for The New York Times Magazine about Tom Brady, I embarked on a profile of Trump. His political ascendance had mirrored my time reporting on the N.F.L. for my book, Big Game. There were obvious parallels between the circuses. Both offered showcases for American carnage, hubris, and mythmaking. It made sense that America’s chief crossover between reality TV and politics would be obsessed with pro football. Trump had wanted into the N.F.L. Membership Club for years, even though his earlier foray into football with the U.S.F.L.’s New Jersey Generals in the 1980s met with a disastrous end. The U.S.F.L. folded in 1986, and Trump received heavy blame for, among other things, offering exorbitant salaries to lure name players such as Herschel Walker and Doug Flutie to the Generals, even though his counterparts would bankrupt themselves if they tried to keep pace. Trump was also the driving force behind the league moving its games from spring to fall to compete directly with the N.F.L.

From the start, Trump’s motive with the U.S.F.L. was to get himself into the N.F.L., either through a merger or by making the Generals so enticing that the big boys could not refuse him. Trump, in 1984, finagled a meeting with N.F.L. commissioner Pete Rozelle at the Pierre hotel in New York, in which he said that he would do whatever it took to get into the league. Rozelle was not impressed, according to an account of the meeting by Jeff Pearlman, author of an upcoming book on the U.S.F.L. “They just saw him as this scumbag huckster,” Pearlman said of Trump. “He was this New York, fast-talking kind of con man.”

The N.F.L. had long factored in Trump’s well-documented Wannabe Complex: his craving for acceptance from the real billionaires and real tough guys whose ranks he desperately wanted to join. His most recent play for entry came in 2014, when he attempted to buy the Buffalo Bills, a franchise that was most definitely not tired of winning. No one thought Trump was serious. They figured it was just another one of his publicity stunts, like running for president, something that would never (ahem) amount to anything. Trump did not come close to passing muster with the Membership. He was, for starters, not considered sufficiently solvent or transparent to proffer a serious bid. Football owners, as it turns out, get a much closer look at a candidate’s finances than electorates do. The Bills wound up selling to the Pennsylvania shale-fracking magnates, Terry and Kim Pegula, for $1.4 billion. This was disappointing to Trump, who was, in fact, very serious about wanting the Bills, and was reportedly one of the three serious candidates for the team. (The third was a Toronto-based investor group that included Jon Bon Jovi, an owner of the arena league’s Philadelphia Soul.) Trump became upset with Patriots owner Robert Kraft, his longtime friend, wishing that he had done more to grease his entry with the Membership board. It created a rift between the two that lasted until the summer of 2016, when Kraft approached Ivanka Trump in Aspen and told her how much he missed Donald, who had recently become the newly minted Republican presidential nominee.

As for the Bills, Trump took the loss with his customary grace and magnanimity. He assured fans via Twitter that he had dodged calamity. “Wow. @nfl ratings are down big league,” he wrote shortly after the Pegulas bought the team. “Glad I didn’t get the Bills.” This feeling was quite mutual and considerably more sincere coming back from the league. But Trump, as he does, would not let the matter go. “Even though I refused to pay a ridiculous price for the Buffalo Bills, I would have produced a winner,” he tweeted a few days later. (These were more innocent times, before D.J.T.’s tweets were poking at nuclear-armed madmen.) In the end, a seat at the N.F.L. Membership table is so exclusive that even the White House itself has become a consolation prize.

By no means, though, was Trump done with the N.F.L. Trump knew I had profiled Brady earlier, and he would not shut up about how he and the handsome quarterback were special friends. They initially met in 2002 after Brady led the Patriots to their first Super Bowl win, and Trump enlisted him to judge the Miss Universe pageant in Gary, Indiana. “If one thing stands out about Tom Brady,” Trump told Sports Illustrated at the time, it “is that he loves those women. And guess what? They love him, too.” Trump even tried to offer up Ivanka to Brady at the pageant. “I think he and Ivanka would make a great combination,” Trump told Howard Stern. The mind recoils: in a parallel universe, Brady could now be filling the powerful son-in-law role in the West Wing, quarterbacking Middle East peace talks.

Donny and Tommy golfed together a bunch of times over the years. Trump would call Brady after his games, and, sometimes, if the call came in when Brady was driving home from the stadium, he would put Trump on the speakerphone for the other passengers to hear—because it’s such a kick to have the actual voice of Donald Trump coming over the phone; and it was for Trump, too, to have Brady’s on the line (also on the speaker). This is one of these mutually fetishistic dances that the Very Famous engage in. What’s the use of having shiny friends if you can’t show them off? During one of our encounters amid the campaign, Trump showed me the Patriots helmet and autographed Brady football next to his desk at Trump Tower. He kept bringing up Deflategate, which he also called a “witch hunt” and seemed more interested in discussing than many of the policy issues that were coming up in the campaign. “It’s so ridiculous what they’re doing to him,” Trump said of Brady, mentioning again that he had just spoken to Tom. “He said: ‘Mr. Trump’—he calls me Mr. Trump, which he shouldn’t, because we play golf all the time. Anyway, he says: ‘Mr. Trump—Donald.’ He doesn’t even know what the fuck to call me. It’s the craziest thing. He’s a friend of mine. A really good friend of mine.”

Standing across the room was the not-yet-famous Hope Hicks, Trump’s ever-present campaign press aide and the future White House communications director. Her father, Paul Hicks, was then the top flack (sorry, executive vice president for communications and public affairs) at the N.F.L. But Hope happened to mention that he had just resigned that morning. “You’re kidding. What happened?” Trump asked her. “It was just too much, right?” Trump replied (to his own question). “He probably thought, ‘You people are crazy.’” Hope shrugged, nodded.

A few weeks later, the future president was showing me around Trump National Golf Club in Rancho Palos Verdes, California. We were accompanied by Damon Winter, a New York Times photographer who had, a few months earlier, photographed Brady for the earlier profile. At one point, as Trump showed me around his 7,242-yard golf paradise on the Pacific, he looked over at Winter. “Who’s got a better body, me or Tom Brady?” he asked. No answer from Winter that I recall. Trump kept urging me to call Brady and ask him about his “great friendship with Trump.” Brady would say great things, no doubt. “Ask him, ‘How is Trump as a golfer?’” After Trump kept insisting, I finally reached out to Brady, fully expecting a polite stiff-arm from the quarterback. “I really have no interest in political talk right now,” Brady confirmed promptly. “I have learned way too much about politics the last seven months.”

This is an adaption of Big Game: The N.F.L. in Dangerous Times, by Mark Leibovich, published by Penguin Press.