The building that is in the process of becoming the Trump International Hotel Washington D.C.—a century-old granite behemoth that has served as postal headquarters, government offices, and a retail mall—sits cheek by jowl with an IRS building. “We’re going to work out a really good rate for them,” joked Donald J. Trump Jr., who is developing the property on behalf of his father, as he led me around the site one sunny morning this spring. “Maybe that will stop some of these ridiculous audits!”

Trump fils, the firstborn and namesake of the presumptive Republican presidential nominee,* is an executive vice president of the Trump Organization, where his projects include the D.C. hotel. Don, as he is known to friends, is strapping and tanned, with a chestnut-brown mane that he wears aggressively gelled back from his forehead, having apparently learned from his father to pick a hairdo and stick with it.

Other than a stint on The Apprentice, Don has generally kept a low public profile. But as Trump père’s presidential campaign gained traction last year, he emerged as an adviser to and a political surrogate for his father. In Iowa in January, he accompanied a group of reporters on a pheasant-hunting trip; a few days later, on caucus night, he mingled with voters at a suburban mega-church. In an interview, Donald Trump told me that his eldest child was “doing a really good job for me.” He added that, of his children, Don was the most natural salesman, with instinctive people skills. “We have different styles—maybe his is better than mine, frankly,” Donald said. “People like him a lot, and people trust him.”

The day I met up with him, Don had caught a ride from LaGuardia airport on his father’s 757. Donald had a day of meetings in D.C. with his national-security team, interest-group representatives, and the Republican National Committee; Don wanted to check on progress at the hotel. “Washington is a greatly underserved market in the luxury sector, without question,” he told me as we walked across the future hotel’s bare concrete floors, stepping over electrical cords and around shrink-wrapped pallets of acoustic tile. Diplomats, CEOs, and other bigwigs visiting the nation’s capital don’t have many high-end lodging options, he said. “We have a real opportunity to stand out.”

If official Washington has tended to regard Donald Trump as an invader, the hotel project has gotten a slightly warmer reception. Erected in the 1890s, before Washington restricted building heights, the nine-story Old Post Office Pavilion is the city’s second-tallest building, not counting the Washington Monument, with a clock tower jutting 315 feet into the sky. But by 2012, when Trump’s company was chosen in a competitive bidding process to redevelop the once-grand castle, decades of wear and tear had left it decrepit. In exchange for a 60-year lease, Trump promised that $200 million would be spent on the renovation.

With the hotel scheduled to open in September—its 263 rooms will start at $550 a night—both father and son like to joke that, no matter how the election turns out, Trump will soon be on Pennsylvania Avenue. Already, tourist buses have taken to stopping before the billboard-size royal-blue sign out front that reads coming 2016: trump. (One D.C. councilman suggested that the sign might constitute “inappropriate” campaign advertising, but officials ruled that it qualified as temporary construction signage and was thus kosher.) “People get out to take pictures in front of the sign and post them on social media,” said Mickael Damelincourt, the property’s managing director, as we strolled from the main building to the 13,200-square-foot ballroom-in-progress. “Which is fantastic for me in terms of awareness!”

In his campaign, Donald Trump has inveighed against Washington lobbyists, claiming they control politicians like “puppets.” But those same lobbyists will be the target market for the hotel, which is in the center of the city’s power corridor, roughly equidistant from the White House and the Capitol. “We are at ground zero for all the big lobbying and law firms,” Don told me as saws buzzed in the background. “When this is the lobby and bar area”—he swept an arm around the building’s atrium—“it will be a perfect power-breakfast spot or après-work drinking spot.”

Plans for the hotel’s restaurants were complicated when two celebrity chefs, José Andrés and Geoffrey Zakarian, pulled out of the project to protest Donald Trump’s statements about immigrants. (The hotel’s 220-seat flagship restaurant, which will feature a balcony overlooking the atrium, is now slated to be a BLT Prime steak house.) But Don insisted that the Trump campaign hasn’t otherwise had much effect on the Trump business—if anything, he suggested, the reverse was true. In 2008 and 2012, he said, Donald decided against running for president in part because he worried that his children were too young to take over the Trump Organization’s day-to-day operations.

Now Don is 38, and has worked for the company for a decade and a half; his siblings Ivanka and Eric, who are also executive vice presidents at the company and have a hand in the hotel project, are 34 and 32, respectively. Don says this made it easier for his father to step away from the business—though he still keeps a close eye on operations. In mid-March, when Donald held a press conference at the hotel site, he praised the facility’s bathroom fixtures before taking questions about foreign aid and delegate counts.

Growing up in the penthouse apartment on the 68th floor of Manhattan’s Trump Tower doesn’t make for a normal childhood. “But I guess it’s what I know, so it doesn’t seem as unusual as it probably should,” Don said, settling into a folding chair in a construction manager’s bare-walled office off the hotel atrium. He wore a slim-cut blue suit, dark-brown tasseled loafers, a tie with a blue-and-purple print, and a wide-collared shirt with djtjr embroidered on the cuffs. As we talked, a staffer flitted into the room to offer miniature bottles of Trump-brand spring water, the U on the turquoise-blue label replaced by the family crest.

Aided by nannies, Don’s mother, Ivana, took the lead on day-to-day child-rearing; his father would see him off to private school each morning with a hug and a lecture consisting of “ ‘No smoking, no drinking, no drugs,’ ” he recalled, “usually followed with ‘Don’t trust anyone.’ ” Donald wasn’t the type of dad to take his kids out to the backyard—“or, in our case, the roof of the building”—to throw a ball around. “He made time for us,” Don said, “but it was always on his terms.” That often meant Don accompanying his father to construction sites, or playing with toys at the foot of Donald’s desk while he negotiated a deal.

As a boy, Don spent more than a month every summer with his maternal grandfather, who was an electrician in Zlín, a Moravian industrial town several hours east of Prague. He perfected his Czech and also spent many hours alone in the woods, an experience he credits with teaching him the virtues of both the outdoors and a modest life. “When you got back from that, you appreciated what you had,” he said, “but you also appreciated that people who don’t have a lot still have the most important things: relationships, time around the campfire.” Don’s mother describes his childhood journeys in somewhat more glamorous terms. “I would drag all my kids through Europe,” Ivana told me, laughing. “I would take them on the yacht in the summer to the south of France, to Italy, to Greece, to Corsica. They were very well traveled.”

Don was 12 when it emerged that his father was carrying on with a younger woman, the Georgia beauty queen Marla Maples. What followed was hard on the Trump children: photographers camped out at Trump Tower, months of lurid headlines (one New York Post cover blared Maples’s alleged assessment of Donald: “BEST SEX I’VE EVER HAD”), ridicule from classmates. Ivana won full custody of the children and moved them to an Upper East Side townhouse. Don didn’t speak to his father for a year, and at age 13, he left New York for an all-boys boarding school in Pennsylvania.

Don was a stubborn and rebellious teen; as an undergraduate at the University of Pennsylvania’s Wharton School, he was known for his raucous partying. After graduating, he moved to Aspen, Colorado, where he worked as a bartender and lived a ski bum’s life. (Ivana says she and Donald “were not that sure” at the time that Don knew what he was doing.) Don told me he always knew he’d go into the family business, but first wanted to see the world to make sure he didn’t wind up like “a lot of people who spend 10 or 15 years dedicating their lives to a career that they hate, only to wake up and say, ‘What have I done with my life?’ ” Shortly after September 11, 2001, he moved back to New York.

Today, Don and his wife, Vanessa, a model turned stay-at-home mother, have five young children and live in Manhattan. Despite his father’s wealth, Don has a mortgage: “We were never really trust-fund kids,” he says. “We work.” An avid outdoorsman, he boasts that he has not spent a weekend in the city in a decade, preferring to take the kids out of town to hike, fish, and hunt. His slaying of an elephant on a big-game hunt in Zimbabwe several years back drew criticism from animal-rights groups, though the government confirmed that the hunt was legal. This year, an old photo of Don holding the elephant’s severed tail circulated on Twitter along with the observation that it was perhaps “the best accidental metaphor ever.” When I told Don about the tweet, he laughed: “I never thought about it in those terms!”

Don seems unperturbed by suggestions that his father might destroy the GOP. “The Republican Party as I know it hasn’t exactly done a good job of anything lately,” he said. “It’s not like they’ve exactly given us winners.” By holding candidates to what he described as a 10,000-point litmus test, he believes, Republicans have narrowed the party’s appeal and isolated themselves from the national mainstream. “If the Republican Party were a business, you wouldn’t have the same people still running it,” he added.

As workers painted the presidential suites upstairs (they come in three sizes, ranging from 2,000 to 6,000 square feet—apparently not all presidents are created equal), Don explained his disdain for what he sees as a moribund political establishment. “So many people in politics are just so unimpressive, they’re just part of the revolving door,” he said. “That’s probably why the establishment on both sides hates my father so much, because if I see it, he certainly has.”

Don got worked up as he talked about politics, gesturing with his hands, sputtering in exasperation, and doing big-voiced impressions of those holding the viewpoints he was mocking. He described his political views as fiscally conservative and pro–Second Amendment but said, “There are quite a few social issues that I don’t understand.” He declined to elaborate on his positions on the record, though in a 2012 radio interview he said that he favored abortion rights and gay marriage. On immigration, however, he sides staunchly with his father, who has called for a wall along the Mexican border and a ban on Muslims entering the country.

“As a businessman, if you just let everyone in, yeah, I could hire cheaper labor, I would save money,” he said. But American workers’ wages are undercut by illegal immigrants, he contended. As for Muslim refugees, Don said, “When you see what’s going on in Europe the last few months, sure, okay, it’s great that we want to be welcoming! I’d love to be welcoming if everyone was like me or like you!” But, he continued, the fact that many refugees are “young, single males, versus guys with families and kids,” gives him pause. “It’s so staggeringly disproportionate that it’s hard not to think of it as a potential Trojan horse.”

In early March, Don became the subject of a minor controversy when a Tennessee radio host who’s been described as a white supremacist claimed to have interviewed him. Don explained to me that he had been doing a spate of radio interviews by phone from his office in New York, including one with a conservative Utah talk-radio host. The alleged white supremacist, James Edwards, was also a guest on the show. According to Don, when Edwards began questioning him, he had no way of knowing whom he was talking with. “It’s so fake, it’s such a nonstory,” he said. “But now, the rest of my life, if you look online, you’ll see a story about me cavorting with white supremacists.”

No matter how disruptive Donald’s current venture may be to his children, Don’s loyalty to the Trump cause is unwavering. When I pressed him on whether Donald ought to do more to discourage violence at his rallies, Don said, “I don’t think anyone’s encouraging anyone to punch someone in the face”—though at a February rally his father did tell the crowd, after a protester was removed, “I’d like to punch him in the face.” Asked whether he might himself run for office one day, he didn’t rule it out: “Like my father, I never take all the cards off the table.”

Don claimed not to understand the idea that he might resent living in his father’s long shadow. Yet there are clearly downsides to having a polarizing politician in the family: When I mentioned my upcoming vacation to Mexico, he mock-plaintively asked me to smuggle him in my suitcase. He used to spend a lot of time there. But he had a feeling that Trumps—particularly ones named Donald—might not be welcome south of the border these days.


* This article has been updated to reflect the fact that Ted Cruz and John Kasich suspended their campaigns after the June issue went to press.