That one of those managers was his wife, Ivana Trump, but didn’t earn her any slack.

“His tactic there, as our success surpassed the Castle’s in 1987, was to shove the Plaza’s performance in Ivana’s face, like a mirror, holding it up for her to see the reflection of a less than successful manager,” John O’Donnell, Ivana Trump’s rival in the casino wars, wrote in a 1991 book.

Trump’s penchant for encouraging rivalries is now roiling his presidential campaign just as he’s captured the GOP nomination, creating deep uncertainty among Republicans about his preparedness for a complex and costly general election campaign. The tensions boiled over last week with the abrupt ouster of political director Rick Wiley, who left the campaign after just six weeks.

Wiley found himself caught between Trump campaign manager Corey Lewandowski, one of the businessman’s original campaign staffers, and Paul Manafort, a veteran Republican hand who was brought in to bolster the operation in March. While Wiley was originally hired by Lewandowski, he aligned himself with Manafort’s vision of a more robust and expensive campaign operation—a vision Trump does not appear to have fully bought into. He also was seen as being unwilling to fill top jobs in battleground states with people close to Lewandowski, according to people familiar with the decision.

Wiley did not respond to requests to discuss his tenure with the Trump campaign. Trump aides would not make the candidate available for an interview, but they did not dispute the notion that the real estate mogul encourages internal competition.

“Of course there’s competition because you want the best,” Lewandowski said. “That’s the type of mindset you have to have in the federal government.”

Sam Nunberg, a former Trump aide who was fired last year, put the dynamic more bluntly: “He loves playing people against each other.” Still, Nunberg said he appreciated the competitive environment, crediting it with keeping staffers creative and committed to the organization.

But for other Trump aides, the businessman’s cutthroat style led to mistrust and paranoia

“You can’t trust the other guy’s people,” said Stuart Jolly, who resigned as Trump’s campaign field director after Manafort and Wiley were given more power. Jolly confirmed Friday that he is joining the pro-Trump group Great America PAC as its political director.

Some current and former Trump advisers blamed the businessman for withholding information about staff changes from his team, sometimes leaving them to learn about internal developments in the media. Some have taken to shopping negative stories about their rivals to the press in a bid to undercut each other in the eyes of the boss — even if the stories reflect poorly on Trump.

Even more concerning for Trump as he eyes a likely faceoff with Democrat Hillary Clinton is the uncertainty the internal friction has created about the direction of the campaign. People close to the campaign say there are major questions about battleground state hiring, voter-targeting efforts, and super PAC fundraising.

Those close to the campaign insisted on anonymity because they were not authorized to discuss the campaign publicly.

Trump turned his fondness for competition into ratings gold with his television show “The Apprentice,” where rival teams battled against each other to impress the boss. Those who failed were unceremoniously fired—a made-for-television version of events that sometimes played out in Trump’s real businesses.

In 1985 and 1986, Trump acquired full control of two Atlantic City casinos in quick succession. Ivana Trump was put in charge of one, named Trump Castle, while the other—Trump Plaza—was overseen by casino managers hired away from gambling titan Steve Wynn.

Castle and Plaza managers were expected to compete over everything from casino entertainers to which property bought more copies of Trump’s autobiography, “The Art of the Deal.”

The most heated competition of all: which casino could draw the high-rolling gamblers who would wager thousands of dollars per hand. By 1987, the larger and more luxurious Plaza was successfully wooing this small but elite set, aided by top-tier prize fights in the Atlantic City Convention Center next door.

Instead of allowing the Plaza to establish itself as the unrivaled venue for high-rollers in Atlantic City, however, Trump underwrote Ivana’s campaign to compete for them.

“If we presented a $100,000 player with a gold Rolex watch, the Castle gave him two,” O’Donnell wrote in his book “Trumped! The Inside Story of the Real Donald Trump — His Cunning Rise and Spectacular Fall.” In a 1997 interview, Trump said “the stuff O’Donnell wrote about me is probably true,” using an expletive to describe his former executive as a loser.

When Plaza managers pleaded to Trump that the competition between his two casinos was ill-advised, Trump mocked them.

“What are you worried about Ivana for,” he told one executive, according to O’Donnell’s book. “She’s just a woman. She can’t take the business.”

The competition described by O’Donnell led to an ill-advised, $70 million addition to Trump Castle, dubbed “The Crystal Tower,” and continued even after Trump sent Ivana back to New York and three of the Plaza’s top executives died in a helicopter crash.

Within weeks of the accident, Trump’s Castle team launched a surprise raid on Trump’s other casino: It’s top executive leased office space directly above the Plaza’s marketing department, offering the Plaza team raises of up to 30% to defect.