Then, in 2002, Survivor creator Mark Burnett came to see him at Trump Tower. Burnett, a former T-shirt salesman on Venice Beach, had achieved stratospheric ratings with a show based in exotic spots such as the Australian outback and the Polynesian islands. But he had little kids at home, and he was desperate to do a show in a United States city. Burnett's road home, he realised, was through Trump.
The Apprentice would star Trump as judge, jury and executioner in a weekly winnowing of young go-getters vying to run one of his businesses. Trump's agent told him it was a terrible idea - business shows never work on TV, he said.
Trump disagreed. Indeed, he fired the agent shortly after. "If I would have listened to him," Trump told the Washington Post, "I wouldn't have done the show."
"My jet's going to be in every episode," he told Jim Dowd, then NBC's publicity director and now head of a PR firm, Dowd Ink. "Even if it doesn't get ratings, it's still going to be great for my brand."
Burnett walked out of the meeting with a handshake deal. Trump secured not only a starring role on a show made by TV's hottest producer but also a 50 per cent ownership stake in The Apprentice. The man who now seeks to be commander-in-chief had consulted no one, done no research. He liked the idea. He bought it.
It was a classic Trump moment, an example of the gut-instinct decision-making that he proudly touts in nearly every campaign speech. Buy a show. Build a wall. Pull out of a debate. Make America great again.
"It's very easy," Trump promises.
What was harder was the decision to run for president, which Trump had talked about for decades. He didn't run for president because of The Apprentice, but according to the show's executives and producers, without The Apprentice there would be no candidacy.
The lightbulb moment for the show that would change Trump's trajectory came in 2002, when Burnett was filming the finale for Survivor: Marquesas - in New York's Central Park at the Wollman ice rink. Trump operates the skating facility, having famously renovated it in a jiffy and under budget after the city government spent six years and US$12 million ($18.5 million) failing to fix it.
Burnett, fed up with being stuck in the jungle "with crocodiles and ants and everything that could kill you", decided his next show had to be set in a different kind of jungle, made of asphalt. "What I needed was someone larger than life, very colourful," he said, a character who would be likable, tough and fascinating enough to interest an audience through a whole season.
Jeff Zucker, then president of NBC Entertainment, and Jeff Gaspin, then the network's chief of reality shows, were both New Yorkers who had seen firsthand how the city's tabloid newspapers dined out on Trump's showmanship. They knew there was more to Trump than people outside the New York area might have seen.
They were right. The Apprentice was an instant hit when it debuted in 2004, quickly amassing an audience of more than 20 million viewers.
The plan NBC bought envisioned Trump as host for only one year.
That notion fell by the wayside during the taping of the first episode. The script called for the host to play a modest role in each instalment, introducing the challenge that contestants faced, then returning for a brief boardroom scene at the end to decide who had performed poorly and would not be coming back.
In the boardroom NBC built for him inside Trump Tower, Trump took to his role instantly. The taping went on for nearly three hours, and "it was only when we saw rough cuts of the boardroom scenes that we realised they were gold", Gaspin said. "After the first episode, we said we want more Trump."
What would become the show's catchphrase, "You're fired," was not scripted, Trump and the producers agree. When Trump blurted out the words, the crew in the room instantly knew this would be the show's signature phrase.
But although "You're fired" became a symbol of Trump's blunt toughness, a look back at the show's first season reveals something different: pauses and a softening of the voice just before he sacks a contestant, and frequent consultations with his staff, whose views he sometimes adopted even when he disagreed.
What the audience saw on TV altered their perception of the mogul they had known as an immodest dealmaker who built glitzy towers, married beautiful women and slapped his name on jets and yachts.
The Apprentice turned Trump from an easily caricatured Richie Rich who had just weathered some difficult years into a pop-culture truth-teller, an evangelist for the American gospel of success, a decider who insisted on standards in a country that had somehow slipped into handing out trophies just for showing up.
"Donald was about honesty. He was tough but truthful," said Gaspin, who went on to be chairman of NBC Universal Television Entertainment. "He wasn't saying you were good at your job when you weren't."
The Apprentice let Americans see Trump in a way they perceived as unmediated.
On TV and on the campaign trail, "people want to hear the unvarnished", Burnett said. "Without a TV show, you are just the editor's headlines, the journalist's take. On TV, you feel you get to know the person. That same style that he showed on The Apprentice seems to be what's working for him now - the ability to speak his mind clearly and not tone down his voice in a politically correct, TV way. It's the kind of brand recognition that would certainly enhance your political career."
Those who knew him before The Apprentice saw a character emerging on the show who was basically the same as he was off-camera, a man who loved power and success but who also won people over by being frank and listening well.
Trump scoffs at any effort to psychoanalyse his performance. He says he did the show in good part because "it's lucrative, even if you're rich". But in his most recent book, Trump writes that he did The Apprentice "because it creates such a powerful brand presence and is a lot of fun to do". And it allowed Americans to see a more nuanced version of him.
"I do have great feelings for people," Trump told the Post. "But I became more popular by being on a show where I fire people. It's weird. I am an honest person. Michael Douglas said I'm the best actor on television. I said: 'I'm not acting. This is who I am'."
The show's instant success had a powerful impact on its star.
"The Donald Trump I saw the day before The Apprentice premiered was very different from the guy I walked to nine national interviews the first day after the show aired," Dowd said. "People on the street embraced him. He was mobbed. All of a sudden, there was none of the old mocking, the old New York Post image of him with the wives and the parties. He was a hero, and he had not been one before. He told me, 'I've got the name recognition, but I don't have the love and respect of Middle America.' Now he did. That was the bridge to the current campaign." Suddenly, Trump was in demand as never before. Dowd booked him on a morning radio gabfest every week for 18 months. The appearances, initially meant to promote the TV show, quickly veered to talk of politics.
Trump had made noises about running for president in 1988, as a Republican, and again in 1999, when Ross Perot's Reform Party was still barely extant. But The Apprentice made his political aspirations more plausible, he acknowledges.
Trump is quick to note how well known he was before The Apprentice - unprompted, he reels off his ratings on other TV shows, the magazine covers he's graced, the best-selling books he's written - but he says the reality show "was a different level of adulation, or respect, or celebrity. That really went to a different level. I'm running to really make America great again, but the celebrity helped - that's true".
Trump initially saw the show as a brand extension, and with the success of The Apprentice came Trump ties, suits, a fragrance (Success by Trump), lamps, even Trump bottled water.
"Donald calculates the brand awareness," said Burnett, now president of MGM Television Group. "He's a showman."
The show's producers didn't think Trump would really run, but they recall him drawing a direct line from the show's success to the possibility that he would shoot for the nation's top job.
"Donald mentioned a number of times, 'Maybe I'll run for president one day,'" Burnett recalled. "And sad to say, politics is kind of a TV show."