Donald Trump has always professed he's a teetotaler but club owners, models and bartenders who were staples of the New York City nightlife scene in the 1990s have insisted they witnessed the future president drinking, a new book claims.

The real estate tycoon has long maintained he doesn't drink, reportedly in order to make 'consumers of the Trump brand and would-be-lenders believe he always keeps it together,' write Allen Salkin and Aaron Short, authors of the upcoming book The Method to the Madness, released on July 9.

But actually, Trump would spend his time at hip downtown clubs drinking beers, liquor and champagne while using a wingman to help him seduce young European models, according to the authors.

'Sobriety has also been part of the persona he peddles. Let everyone else get sloppy, the subtext goes,' Salkin and Short, both former reporters at the New York Post, write.

DailyMail.com has reached out to the White House for comment.

Donald Trump would drink at NYC hot spots as he chased beautiful young models, according to authors of the upcoming book The Method to the Madness

Trump has long described himself as a teetotaler to make 'consumers of the Trump brand and would-be-lenders believe he always keeps it together.' A bartender said of Trump and his wingman: 'If they could get some large-breasted beautiful young European girl's attention, they would get a nice bottle of wine, sometimes champagne'. Pictured: Trump with Miss USA pageant contestants in 1999

During Trump's 1990s bachelorhood, he was hanging out at clubs in Soho, lounges like Spy Bar, Wax and Chaos that attracted fashion models, artists and some Wall Street sharks along with his late pal, John Casablancas (pictured), the founder of Elite Model Management

During Trump's 1990s bachelorhood, he was hanging out at clubs in Soho, lounges like Spy Bar, Wax and Chaos that attracted fashion models, artists and some Wall Street sharks along with his late friend, John Casablancas, the founder of Elite Model Management.

Trump has always claimed that he never imbibed any alcohol, citing the early death of his older alcoholic brother, Fred Jr., who died aged 43 in 1981, saying in November of 2016: 'I've never had a drink because of my brother.'

He previously said in an Esquire profile in 2015: 'I've never had a cigarette. I've never had a glass of alcohol. I won't even drink a cup of coffee.'

In October of 2018, Trump said: 'I'm not a drinker and I can honestly say I never had a beer in my life. One of my only good traits. I don't drink.

TRUMP'S 'WINGMAN': HOW ELITE MODELS FOUNDER'S MARRIAGE ENDED OVER GIRL, 16 John Casablancas is credited with discovering some of the biggest supermodels, such as Linda Evangelista, Cindy Crawford and Naomi Campbell. The New York native was born in 1942, the son of wealthy refugees from Spain, he enjoyed a privileged upbringing, being educated at a Swiss boarding school. After failing to get a degree in economics in Geneva, Casablancas married Brazilian air hostess Marie Christine in the 1960s. The couple lived in Rio, then Paris, living largely off his trust fund. After beginning an affair with former Miss Denmark Jeanette Christiansen, Casablancas founded Elite in 1972. John Casablancas is credited with discovering some of the biggest names in modeling, such as Linda Evangelista, Cindy Crawford and Naomi Campbell The firm would turn into a powerhouse, making up to $100M a year. After moving the agency to New York in 1977, Casablancas become a city celebrity, dominating its party scene with the world's most beautiful women and partying in legendary nightspots. His sex life was gossip-column fodder. Despite marrying Jeanette in 1978, and fathering her son, Julian, Casablancas pursued a string of public affairs. The most famous, in 1983, was with Stephanie Seymour, a 16-year-old model. He was 41. Jeanette promptly left him. In 1992, Casablancas married for the third and final time to Aime Wermelinger, a contestant in a beauty pageant he was judging. He was 50, she was 17. They went on to have three children. But in 2000 Elite's business practices were exposed with a BBC documentary expose. Executives were caught discussing drug use, making racist remarks and boasting about sleeping with teenage models. Although Casablancas was not personally caught up in the scandal, his playboy reputation did little for the firm's PR image, and shareholders wanted him out. He resigned and sold his remaining stake in the firm. He died while in Rio receiving pancreatic cancer treatment in July of 2013. Advertisement

'I never had a glass of alcohol. I never had alcohol. For whatever reason. Can you imagine if I had? What a mess I would be. I would be the world's worst.'

Most recently, Trump said in April to a group of children: 'Never take drugs, don't drink alcohol, don't smoke. Enjoy your life.'

However, interviewing NYC nightclub owners where Trump frequented in the 1990s, they say he was indeed drinking.

But at least one person denies to the authors that they saw Trump drink while out socializing.

Paolo Zampolli, the founder of ID Models, who introduced Trump to Melania and who was once part of the Trump Organization, said he only saw Trump drink Diet Coke.

He said: 'You could see champagne and vodka on the table, but for sure Mr. Trump had only Diet Coke. That's what he drinks since I've known him.'

Meanwhile, Michael Ault, nightclub guru and owner of the infamous Spy Bar and Chaos, said he witnessed Trump drinking multiple times.

He told the authors: 'We had champagne on the table, always, and we had vodka usually, some scotch. He was drinking champagne or vodka, a liquor.'

A bartender who goes by Laraby also recalled Trump drinking, saying: 'I served him and he drank at the bar. He'd come in with John Casablancas.

'He'd go to the side of the bar [at Spy] by the waitress station, because he liked the waitresses. He would order light beer. It was usually Miller Lite or Bud Light. John ordered vodka-based drinks.

'If they could get some large-breasted beautiful young European girl's attention, they would get a nice bottle of wine, sometimes champagne, and move to a table.

'He drank his beer out of the bottle. He would nurse his beer. Even if they were there for hours, he would have three beers at the most.

'Trump was very f**ing awkward and it was like John was Trump's wingman to get him laid. This was his dynamic'.

Model Caron Bernstein said: 'I was at clubs like eight nights a week in those days and ran with an entourage.

'The night would start at a place called Pure Platinum on 21st Street, which is basically a strip club. There'd be all these girls that were known for their bodies, like Maureen Gallagher.

'They would get onto the poles with the strippers. It was more lax about doing drugs out in the open in public than the regular nightclubs, so we would start the night out at these strip clubs and it became a frenzy. I would see [Jeffrey] Epstein, Trump, like all the old geezers, at that place too. It would be the prequel to whatever club we were going to.'

He was also a lousy tipper, Laraby claimed to the authors.

'If Trump was paying for his beer, John's drink and the bottle of champagne, he'd leave me, like two dollars,' Laraby said. 'He'd have a wad of cash, and he'd leave me two dollars. I wanted to kill him'.

Club owner Ault added: 'I would hear from the doorman that he was on the way to our table. I'd think, Oh, it's going to be one of those nights.

'People talk about how he's such a genius PR guy and marketing guy and I guess that's true.

'But it felt like you were in the presence of someone who was constantly selling you something... talking about his successes.

'He didn't want to know how my day was but he was certainly prepared to talk about how his day was. It was boring.'

Trump had developed an old-school habit of checking in for a six-minute conversation with at least 10 people a day, talking about himself, which helped him stay current.

He was always self-promoting, calling New York tabloid newspapers and talk shows with outrageous but quotable opinions – enough to always have his name in print but with the one requirement: the word 'billionaire' had to appear before his name.

When asked in 1998 by political commentator Chris Matthews why he didn't run for president, Trump responded: 'Can you imagine how controversial I'd be? You're thinking about Clinton with the women? How about me with women?'. Pictured: Trump surrounded by women at his birthday celebration in 1994

Trump has always claimed that he never imbibed any alcohol, citing the early death of his older alcoholic brother, Freddy, who died aged 43 in 1981 (pictured together in a family photo)

In late 2018, Trump said: 'I'm not a drinker and I can honestly say I never had a beer in my life. One of my only good traits. I don't drink. I never had a glass of alcohol. I never had alcohol. For whatever reason. Can you imagine if I had? What a mess I would be. I would be the world's worst.' Pictured: Trump appearing to sip out of wine glass while toasting at a United Nations luncheon in 2017

SPY BAR: THE NYC LOUNGE THAT INTRODUCED BOTTLE SERVICE TO THE WORLD Opened in 1995 on Greene Street in Soho, Spy quickly became one of the hottest lounge bars in the city. Owned by nightlife guru Michael Ault, the spot is credited with bringing bottle service into the nightlife scene in NYC, before spreading throughout the world. The joint became so high profile with people clamoring to get in, even supermodel Kate Moss was reportedly turned away once. The lounge atmosphere inspired dozens of copycats, but none outshone the original. Music journalist Lonn Friend recounts seeing Donald Trump with Van Halen singer David Lee Roth at the iconic spot. Friend said in an interview: 'I look down and at the V.I.P. table in the front and I see Donald Trump and David Lee Roth. 'Like together with two hot chicks and I couldn't help but walk over to Dave and lean over to Dave and go ''Dave, it's Lonn from RIP magazine'' and he goes ''How's it going man, good to see ya.'' 'I said ''I have just one question, who made the call? You or Trump? How does this happen?'' He didn't even have an answer. He just smiled at me.' Advertisement

This was 'the Donald, the gossip-page fixture who blasted enemies, publicized the gauche luxuries of his condo properties and drove his mistress to proclaim on a tabloid front page that she'd experienced – ''Best Sex I've Ever Had'', according to the book.

When asked in 1998 by political commentator Chris Matthews why he didn't run for president, Trump responded: 'Can you imagine how controversial I'd be? You're thinking about Clinton with the women? How about me with women?'

'Trump has a very constant need, a huge appetite for entertainment,' stated Tucker Carlson, a Fox News commentator who was pals with Trump from their days in New York City in the 1980s, rubbing shoulders at nightclubs and society parties.

'He just likes getting out there, flying around in the plane, sitting and bulls***ting with people'.

Television made Trump's persona even more powerful and he developed 'a madness in the method evident in the savageness with which he levels a personal attack,' write the authors.

When he went after Barack Obama with the birther mongering, Trump had learned from his mentors Roy Cohn and Roger Stone that the power of the lie would resonate with voters who already didn't like Obama.

'I got to do what I got to do,' Trump stated. And his outlandish claims got him booked on Fox and The View.

He even confessed off-camera to Mika Brzezinski, co-host of MSNBC's Morning Joe: 'I know it's bad but it works'.

Trump learned he had to play to Americans he calls 'salt of the earth people' and he was tapping into grievances and trying to rally a segment of voters to his side by appealing to their baser instincts.

'That was the first glimpse of the darker side of Donald Trump,' Katie Couric told the authors. 'And the lengths he would go to destroy his enemies.'

For decades Trump puzzled about politics, first preparing to run and talking about declaring his candidacy in 1988 in the New Hampshire primary, a third party bid in 2000 and in 2011, talking about challenging Barack Obama.

In 1999, with Roger Stone's encouragement, Trump was considering opening an exploratory committee for a presidential run on the Reform Party platform discussing lower taxes, railing against NAFTA and saying Germany, France and Japan were 'ripping off' America.

Trump was a 'gossip-page fixture who blasted enemies, publicized the gauche luxuries of his condo properties and drove his mistress to proclaim on a tabloid front page that she'd experienced – ''Best Sex I've Ever Had'' (pictured)

He even floated that his running mate would be Oprah. 'She's popular, she's brilliant, she's a wonderful woman,' he stated.

Trump was learning from Stone, a political consultant and one-time devote of Roy Cohn as well as Richard Nixon, what it was like to set up events to run for President – and he used the 'potential run' as 'tabloid tantalizer and crafty campaigner selling, selling and selling,' write the authors.

He also used the occasion to insult Bill Clinton for his taste in mistresses on the Howard Stern radio show and then handed the phone to his own mistress Melania Knauss, who admitted she was wearing nearly nothing.

Reform Party politician, Pat Choate was unsupportive of Trump moving in on his party but admitted: 'When it comes to honing and trusting his instincts, manipulating the media, branding, collecting useful advisers, engaging in public takedowns, creating and thriving in chaos, adapting winning strategies from others, and dozens of other sometimes subtle methods of getting his way, he is a master.'

After launching what was considered a joke candidacy in 1999, 'Trump spent more than 15 years figuring out how to sell himself effectively in the political world.

'Here is the news – There is a method to the madness,' write the authors.

By January 2000, he was still talking about a run for President on the Reform Party platform, but Melania had called quits on the relationship after finding lipstick smeared on a towel that was from a former flame of Trump's, model Kara Young.

He had to get Melania back after saying what a great First Lady she'd make. And he did by month's end.

For decades Trump puzzled about politics, was preparing to run and talked about declaring his candidacy in 1988 in the New Hampshire primary, a third party bid in 2000 and in 2011, talking about challenging Barack Obama. He even floated that his running mate would be Oprah (pictured together in 1988). 'She's popular, she's brilliant, she's a wonderful woman,' he stated

When he went after Barack Obama with the birther mongering, Trump had learned from his mentor, Roy Cohn (pictured together in 1984) and Roger Stone that the power of the lie would resonate with voters who already didn't like Obama

But he concluded he couldn't win the race as an independent and that the country wasn't ready for an outsider businessman as president – with his 'reputation as a modern day PT Barnum looking for the next big thing,' write Salkin and Short.

Trump kept plotting a 2012 presidential bid while fanning birther rumors and leaning on Michael Cohn and Roger Stone, according to the authors.

He didn't use a computer and had a flip phone but then advisers taught him how to use Twitter – and he was off and running.

Even Tucker Carlson admitted that the race angle Trump was playing came from an impulse Trump has, 'not all good by the way. It's bad,' he's quoted in the book.

On the birther comments, Jared Kushner told Elizabeth Spiers, one-time editor in chief at the New York Observer newspaper that Jared once owned, 'Oh, he doesn't believe that stuff. He's just saying it because he thinks Republicans are dumb and they'll buy it'.

Even media executive and former strategist to Trump, Steve Bannon views him as a true barbarian.

'He's not from the system. He's Archie Bunker from Queens. He's not watching Meet the Press, going to church or going things normal humans do,' Bannon stated.

When Trump rode that escalator in Trump Tower down to finally declare his candidacy in 2015 (pictured), one of his many advisers, attorney and political strategist, Sam Nunberg, wanted this declaration to be 'the most smash mouth, disgusting – I mean in a good way – f**k you to everything. It was glorious. Terrible. We're different. We're here. Get over it', he stated

'Sobriety has also been part of the persona he peddles. Let everyone else get sloppy, the subtext goes,' the authors of The Method to the Madness write

Trump was using gonzo politics, hard-right American politics.

'I love my enemies and I love having enemies to a certain extent – that's probably a mental sickness. But you need it. It invigorates,' Trump stated.

He learned to say outrageous things so newsworthy that he sucked all the oxygen out of the room.

'I'm going to do it again until every one of the other opponents dies off from lack of oxygen,' Trump said when he entered the presidential race in 2015.

'He's a showman. He understands a good turn of phrase and memorability. He understands the importance of memorability,' Roger Stone said.

When Trump rode that elevator in Trump Tower down to finally declare his candidacy in 2015, one of his many advisers, attorney and political strategist, Sam Nunberg, wanted this declaration to be 'the most smash mouth, disgusting – I mean in a good way – f**k you to everything. It was glorious. Terrible. We're different. We're here. Get over it', he stated.

Some found it hard to believe that Trump, good for an attention and getting gossipy quotes, was actually so methodical in seeking the Presidency that all of his talk show appearances weren't just to promote the Apprentice, flaunt his casinos, his deals, 'a university', the women he was dating or a new Trump product.

Allen Salkin and Aaron Short's The Method to the Madness is available on July 9.