Donald Trump greets supporters at a football game in Ames, Iowa, over the weekend. He has few advisers and refuses to use a computer. Source: AFP

Seated in his plane’s living room, with its pearlwood and 24-carat gold trim, Mr Trump worked alone, watching the big-screen TV and reading the day’s political news, mostly about him, with no binders of policy positions or talking points in sight. Upon landing, he waded alone into a throbbing mob desperate for his autograph at a packed Nashville rally.

It all fit the rule for staffers scrawled on a white board at campaign headquarters: “Let Trump Be Trump.”

The 69-year-old billionaire has soared to the top of the Republican field flying solo — a man and his plane, propelled forward by a gust of free media attention and virtually devoid of the staff, position papers, opposition researchers and ad budgets of modern campaigns. Now, though, with the time for summer flings ending and more serious voter examination just ahead, the Trump effort has reached an inflection point, at which he must decide whether he can continue to prosper as this kind of one-man show or whether the time for that is running out.

Travels and extensive conversations with Mr Trump in recent weeks show that, while he is ­slowly beginning to bend to some candidate norms — opening state offices, readying ballot-access drives and preparing a tax plan — he continues to resist the experts’ view that he needs a conventional campaign apparatus.

“A lot of what I’m doing is by instinct,” Mr Trump said in one of several interviews. “I assimilate a lot of information … and I believe in being strategic.”

Instead of surrounding himself with what he called “political hacks”, Mr Trump said, “I don’t need an inner circle.” His rationale: In an “age of specialisation, I am tapping phenomenal people in every field”.

His tax plan, likely to come in the next couple of weeks, will reflect this approach. Figuring that “no candidate ever has known the tax code better than I do”, the longtime businessman issued ­directives: simplify and cut taxes, help the middle class, solve the problem of corporate “inversions” in which companies move headquarters abroad, and “tax the paper-pushing hedge fund guys”.

Without much staff, campaign manager Corey Lewandowski has worked with outside advisers to flesh out the details of the tax plan, particularly to end up with a revenue-neutral result that neither raises nor lowers overall receipts. “We’re running an efficient ­organisation with a business mindset,” Mr Lewandowski said. “We don’t need high-priced staff or consultants when leading authorities are volunteering to help Mr Trump.”

Regarding his own tax rate, Mr Trump said: “I would be happy to pay a lot more if it would help solve our country’s many problems.”

He hasn’t released his tax ­returns but said he definitely would, without specifying when or the number of tax years.

Despite the bare-bones framework he has in place, Mr Trump vows: “I will build a successful campaign for the long haul … I’ve never lost in my life.”

Republican strategist Kevin Madden said Mr Trump faced new and serious threats. “One big question is whether he can turn momentum from celebrity fandom into an actual infrastructure to organise voters in cold gymnasiums in the dead of winter in Iowa. Trump hasn’t seen a full-on ­assault, which is just beginning, with millions of dollars in paid ­advertising and their relentless
attacks.”

Criticism by his opponents is intensifying, calls for him to spell out what policies he believes in are growing, and Mr Trump is entering the phase of the campaign cycle in which previous early GOP sensations have faded or crashed.

Mr Trump is reacting with characteristic bravado. “I hope they attack me, because everybody who attacks me is doomed.”

When he stood in Trump Tower’s lobby on Fifth Avenue in Manhattan to announce his longshot bid in June, few predicted the success Mr Trump has had, not even him. “I had no idea I would do this well this fast,” he said, particularly after he was pummelled for calling some Mexican illegal immigrants “rapists” and “murderers”, which led Macy’s to drop his clothing line and Univision to end the Spanish broadcast of his Miss Universe pageant.

“The first two weeks were very bad for my brand,” said Mr Trump, whose Trump Organisation line of luxury properties includes ­hotels, golf courses and both residential and commercial high-rise buildings. In his office on Trump Tower’s 26th floor, the walls, ­tables and floors brim with testaments to his success — his best-selling books, such as Trump: the Art of the Deal, magazine covers, the chair from which he told contestants “You’re fired!” on the hit reality-TV show The Apprentice.

After that rocky start, his poll numbers rose all summer, shaking up the GOP race and drowning out coverage of other contenders. The presidential bid is turning out to be “very good for the brand”, Mr Trump said. “I’m No 1.”

Jenny Beth Martin, chairman of the Tea Party Patriots Citizens Fund, said the appeal was simple: “A lot of what Trump is saying is what many outside of DC are thinking.”

With autumn arriving, Mr ­Lewandowski is building what he calls an “atypical bottom-up model” of a campaign structure that has as many staff members in Iowa as in Trump Tower. “We get zero votes in headquarters,” said Mr Lewandowski, from the sparse campaign office on the unfinished fifth floor in Trump Tower.

National political director ­Michael Glassner, who along with Mr Lewandowski is among the few seasoned campaign operatives on the staff, said he had been Skyping with potential hires and renting space in states based on the electoral map. He is overseeing the nitty-gritty of ballot ­access in all 50 states and petition drives in the 11 that require voter signatures.

Press secretary Hope Hicks, a one-time Ralph Lauren model who was communications director in the Trump Organisation’s real estate and hotel division, juggles a demanding national press corps and a boss with a penchant for doing his own media. Daniel Scavino, who started as Mr Trump’s caddie in high school and rose to operate one of his golf clubs, is running social media, in which he has been flooded with ­resumes and 98,000 messages in a month. When a court overturned the NFL suspension of New England Patriots quarterback Tom Brady over “deflategate”, Mr ­Lewandowski reminded his boss, a friend of the football star: “Don’t forget to tweet how happy you are that Brady is vindicated.”

When Brady gave his first press remarks, a red Trump “Make America Great Again” hat was visible in his locker.

The campaign website holds exactly one position paper, on the candidate’s now well known ideas for stopping illegal immigration.

Besides a tax plan, Mr Trump said he would begin releasing proposals on trade, healthcare and military and veterans issues.

But he added: “People don’t care about seeing plans. They have confidence in me.”

There is little sign his is turning into anything like a conventional campaign. Over Labour Day weekend, Mr Trump stayed out of sight while other candidates ­paraded and picnicked in early-primary states, “That’s the exact opposite of what works for you,” Mr Lewandowski advised Mr Trump. “We want you where massive numbers of people can hear you and your messages, not a few watching you walk down a street.”

Instead, Mr Trump huddled with advisers who volunteered to prep him for Thursday’s (AEST) debate on military and foreign-policy issues. Mr Trump said he wasn’t cramming, though: “I’ve been prepping for 30 years.”

Mr Trump’s penchant for mocking opponents in his own party, as well as media figures, shows little sign of abating. Asked about a report of his disparaging former Hewlett-Packard chief executive Carly Fiorina with the line, “Look at that face. Would anyone vote for that?” Mr Trump said: “She’s got the wrong persona. I’m not talking about her looks. She failed miserably at HP and in her Senate race.”

Mr Trump also has belittled former Florida governor Jeb Bush’s “low energy” style but now says he is losing interest because “Jeb is just single digits” in the polls. ­Instead, he now directs fire at former neurosurgeon Ben Carson: “Jeb looks like the Energiser bunny compared to him.”

Sometimes, Mr Trump simply ignores the conventions. Before the first GOP debate, candidates were invited to go for a walk-through, microphone check and make-up stop. Mr Trump skipped it all, getting off his plane in time to line up with his rivals right before walking on stage.

His circle of outside advisers is equally unorthodox. Mr Trump recently dined with activist investor Carl Icahn to “energise Carl about dealing with China, Japan and Mexico”, he said. Mr Icahn hosted the dinner on his apartment terrace and recalls telling Mr Trump: “You’re striking a nerve with the people who are tired of getting screwed.”

But, Mr Icahn added: “The rich guys in the Hamptons don’t like you too much.”

Mr Trump’s reply was: “Who cares? They are all giving money to Hillary and Jeb anyway.”

Mr Trump said he was talking to some of America’s “biggest corporate names and finest negotiators” about renegotiating trade deals and making sure the US isn’t disadvantaged. “I’ll give you each a country” to deal with if he wins, he said he has told them.

Another close adviser is his daughter Ivanka Trump, 33, who oversees Trump Organisation real estate and hotel development in addition to heading her apparel and accessories brand. She introduced her father when he announced his candidacy and talks to him several times a day.

Mr Trump said his real estate business was evolving as he campaigned: “As the days go by, I give more and more to my children to run, and my executives.”

His three older children with his first wife, Ivana, run divisions from the 25th floor. His fourth child, with Marla Maples, studies at the University of Pennsylvania, where Mr Trump graduated from the Wharton School.

After work, he rode the elevator to the 68th floor to the penthouse home, decorated in Louis XIV style, that he shares with wife Melania and their nine-year-old son Barron. He emptied his pockets of germicidal hand wipes and $US100 ($140) bills he sometimes hands to volunteers on the trail.

He caught up on news and the other candidates’ actions, as well as some of his own speeches ­recorded by his wife, who is more technologically adept. Mr Trump doesn’t use a computer. He relies on his smartphone to tweet jabs and self-promotion, often late into the night, from a chaise longue in his bedroom suite in front of a flat-screen TV.

Later, in a rare moment of ­reflection, he likened being a candidate to the real estate business and said he considered himself a better builder than marketer: “Just as I’ve built great buildings that sell themselves, I believe in my product now. I’m prepared that if my truth doesn’t sell, the campaign won’t succeed. As in my buildings and my presidential campaign, the people will buy if they want the product. I don’t have to be the best salesman.”

The Wall Street Journal