“Made my night,” tweeted Brad Parscale, approvingly. He was referring to a doctored video in which his head was superimposed on a professional basketball player, leaping up and swatting away from the basket a ball replaced by Joe Biden’s head.

Parscale, 6ft 8in tall, was a student basketball star until his career was snuffed out prematurely by leg and back injuries. He suspects the experience of playing in front of thousands of fervent fans was good training for being a warm-up act at Donald Trump’s rallies.

If Trump wins re-election in November, Parscale, his workaholic campaign manager, will have had a lot to do with it. To admirers, the 44-year-old is an alchemist who turns those seemingly chaotic and raucous rallies into a matrix of data that can predict human motivations and behavior with astonishing precision.

To detractors, Parscale is the epitome of Trumpian Man: a plain-speaking white guy with a Viking beard who makes no apologies, is unburdened by doubt, and embraces a flame-throwing online persona. He is also seen as a chancer who got lucky because of unquestioning loyalty to the Trump family. “He’s an over-promoted troll,” said Charlie Sykes, author of How the Right Lost Its Mind.

Larry Jacobs, director of the Center for the Study of Politics and Governance at the University of Minnesota, added: “Trump is the social media president and Parscale is Trump’s enabler.”

Jacobs drew a comparison with a political consultant to Trump’s most recent Republican predecessor. “Karl Rove was credited as George Bush’s brain because of his strategic brilliance. Parscale is Donald Trump’s social media Rasputin.”

Perhaps it was no surprise, then, that an article co-published last year by the not-for-profit ProPublica and Texas Monthly argued that “Parscale’s accounts of his life and his work for the president comprise a classic Trumpian tale: they’re a combination of hyperbole, half-truths and the occasional fiction.”

He has described himself as a “farm boy from Kansas”, the article noted, but actually grew up on a suburban cul-de-sac. Parscale received a basketball scholarship to the University of Texas at San Antonio until injury struck and eventually studied international business and economics at Trinity University in San Antonio, graduating in 1999.

He told the Guardian in a phone interview: “Early years, I thought I might be an athlete but that stalled on me very quickly as I got a little older and found out it’s actually almost harder to become an NBA player than it is to own a company. I always just saw myself as kind of a CEO, as a business leader. I just wanted to be successful. I was always wanting to adapt but I knew I wanted more.”

Parscale was relatively quick to understand the digital revolution. “In 2001, I took the time to start teaching myself web design. I bought my own URL; I think you can go look it up. I’ve owned it for almost 20 years at parscale.com. I would say that’s as ahead as you can get, right? I would say to my friends, go to my website, and they’re like, how do you go? So that’s early.”

Parscale set up a digital marketing agency in San Antonio which, he says, won local entrepreneurship awards and had more than 700 clients at its peak.

A fan of The Apprentice, he met the Trump family in 2010 and a year later offered a bid of just $10,000 to design a website for Trump International Realty. Parscale told the Washington Post: “I just made up a price. I recognized that I was a nobody in San Antonio, but working for the Trumps would be everything.”

With Trump’s son Eric as his main ally and champion, Parscale and his company went on to land contracts worth hundreds of millions of dollars for work that included websites for Melania Trump’s skincare products, the Trump Winery and the Eric Trump Foundation.

In February 2015, over one weekend on his laptop at home, Parscale earned $1,500 by coming up with a landing page for a presidential exploratory committee. That summer, he built the Trump presidential campaign’s website for $10,000.

As election year neared, Trump’s son-in-law, Jared Kushner, called Parscale to ask how he would run digital strategy for the campaign. Parscale recalled in a Washington Post interview that he told Kushner: “If he wants to be the next president, he has got to harness Facebook. Give me the power, and I can help you win.”

He impressed sufficiently to get the nod as the Trump campaign’s digital director, though he ended up also looking after many nuts and bolts of the hastily improvised operation. He oversaw an under-the-radar advertising operation of a hundred people, known as Project Alamo, in a San Antonio industrial park office building, finally switching to Trump Tower a month before the election.

Crucially, Parscale realized Facebook’s tentacles reached older voters in small towns and rural areas and exploited the platform more effectively than the Democratic candidate, Hillary Clinton.

Trump and Parscale are a good match: mavericks with no prior political experience willing to cross lines once considered taboo. Parscale gained the candidate’s trust. In October 2016, just days before the election, the Bloomberg news agency noted: “Parscale is one of the few within Trump’s crew entrusted to tweet on his behalf.”

Parscale’s companies have been handsomely remunerated by the Trump campaign and Republican National Committee (RNC), although he denies he got rich personally. He told the Guardian: “I got 1% from the ad buy in 2016 and I split that 50% with my partner. I’m now just working flat. I get a flat salary.”

Parscale was handpicked to lead the re-election campaign despite having never been in charge of a political race before. His high status in the Trump family appears to insulate him from the president’s tendency to – like a medieval monarch or tinpot dictator – cast out favourites on a whim.

The 2020 campaign is bigger and better-organised than 2016 by several orders of magnitude but no less demanding. Parscale, a divorcee who has remarried, divides his time between the campaign nerve centre in Arlington, Virginia, and a home in Fort Lauderdale, Florida.

“I have no hobbies,” he said. “My hobbies are watching Fox News, CNN, MSNBC, reading the news and putting on my suit. I do try to read books but that’s mainly for work too. I’ve been reading about every election since 1896 and working my way through. I’ve skipped some years, some of the elections don’t matter as much. I think I’m on my fifth election book right now.”

Trump campaign emails are sometimes sent out with Parscale’s name in the sender column and subject headings such as “I just got off the phone with the president …” Merchandise sales, competition entries, campaign rallies and other forms of contact are an opportunity to harvest more data that will be invaluable for targeted ads and get-out-the-vote efforts.

Democrats are taking note. The Axios website reported: “Trump’s re-election campaign has deployed Facebook in a bigger way than any campaign in history, outspending all the Democrats combined.”

As the familiar soundtrack of Elton John, Queen and the Rolling Stones booms at Trump’s rallies, Parscale has become an increasingly familiar figure on the podium, stoking the flames of crowd anticipation before the main attraction. Behind the scenes, he is also the mastermind of Trump’s slick, hard-hitting and falsehood-strewn campaign ads.

Importantly in 2016, the interloper Parscale made peace with the RNC and now hopes to reap the reward. Republican lobbyist Henry Barbour, a partner at Capitol Resources, said: “He’s very serious about his work. He’s intense, he’s aggressive, he means it. He’s a creative thinker.

“It’s challenging for a guy with his background to manage a campaign. If you had a conventional president, it would be a more conventional campaign. Brad has done a very good job of coming in from the outside and figuring out how to work with the conventional players like the RNC.”

Barbour, chairman of the Republican firm Data Trust and the RNC national committee member for Mississippi, added: “Brad has a thorough understanding of the importance of data and how, having a sophisticated list, you can reach out and communicate the campaign message. He understands that as well as anyone in politics today. If you don’t know who to target, you’re not going to win.”

Indeed, Parscale’s sudden ascent says much about the centrality of digital in today’s politics. Lanhee Chen, a fellow at the Hoover Institution thinktank in Palo Alto, California, said: “I think in 2010, it would have been unimaginable to some degree.

“But where campaigns have come and the degree to which the digital function has penetrated other parts of the campaign, what’s entirely clear is that the digital director or the person who understands the digital side of the campaign is incredibly powerful. It’s a function of where American campaigns have gone generally that the digital strategists are becoming increasingly important and influential.”

Chen, who was policy director for Mitt Romney’s 2012 election campaign, added: “Data is power and the ability to gather data in a way that allows you to really micro-target your message, that’s always been the Holy Grail.”

Can Parscale be trusted with such power? Not according to Kurt Bardella, a former spokesman and senior adviser on the House of Representatives’ oversight committee. “Obviously the formula that they used in 2016 is something they’re going to try to duplicate in 2020, which is really the tactic of using social media to try to distort the truth and mislead the American people and con themselves back into the White House.

“That’s part of the reason why he was made the campaign manager. It shows how much of a priority their misinformation digital strategy is to the re-election campaign.”