Former President Trump blasted ex-CNN boss Jeff Zucker in a new book about his time starring on NBC's "The Apprentice," referring to his one-time ally as "human scum."

In the book "Apprentice in Wonderland," author and Variety co-editor-in-chief Ramin Setoodeh revisits the show that turned a New York real estate mogul into a reality TV star, which ultimately helped propel him into the White House. 

Trump spoke candidly with Setoodeh about his complicated relationship with Zucker, which began when Zucker was president of NBC Entertainment, long before he landed at CNN. 

The book explains that when "The Apprentice" was first picked up by NBC, Trump was initially meant to only host the first season and new hosts would be brought on every season forward. But since "The Apprentice" was a ratings hit, Trump was kept on board. 

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Trump - The Apprentice

Donald Trump was originally supposed to only star in the first season of "The Apprentice" but was kept on after it quickly became a ratings hit for NBC, according to "Apprentice in Wonderland." (Bill Tompkins/Getty Images)

Things were bitter between Trump and Zucker when it came to the second season contract negotiations, according to the book. 

"The $25,000 an episode that Trump earned for the first season of The Apprentice was humiliating," Setoodeh wrote, according to an excerpt published in Vanity Fair on Tuesday. "It wasn’t that he needed the TV money to live off, and the free advertising the Trump Organization got from the series was likely better than any pay package. But it was a status thing: bigger, according to Trump math, was always better. Trump felt that NBC had no choice but to multiply that number by a number so huge it would make him one of the wealthiest men in entertainment."

Trump saw how "The Apprentice" surpassed reruns of "Friends" that aired on the same night and how the six stars of "Friends" each made $1 million per episode by the end of the show's run. But as Setoodeh writes, Trump didn't ask for $1 million per episode. He asked for $6 million per episode instead. 

"'Friends' had six people," Trump told Setoodeh. ‘They’re getting $1 million an episode each. That’s $6 million. So if they’re getting $6 million, and I have higher ratings than they do—because this is the end of 'Friends', and they were fading out—I said, ‘You should pay me $6 million an episode.’"

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That didn't sit well with Zucker, who Setoodeh wrote "became vocally angry that Trump would even consider asking for such an unfeasible payday."

"They went f---ing crazy," Trump recalled. "And they said, ‘We’re not going to do it. It’s over.’" 

Setoodeh writes, "Then Trump counteroffered his own offer. After he kicked off the conversation with a stratospheric number, his strategy was to leave the door open to see what NBC would bring back to the negotiating table. "I said, ‘Here’s what we’re going to do. Give me something less than six. If you’re paying Friends six, and I have higher ratings than Friends, you should pay me six! But give me something less than that. I’m reasonable!’"

"'We’re not doing it,' Zucker hissed to him on the phone. ‘We already have someone else lined up,'" Setoodeh wrote of Trump's conversation with Zucker. 

Donald Trump with Jeff Zucker

Before their 2016 feud, Donald Trump and Jeff Zucker were palling around during their time at NBC. (Frederick M. Brown/Getty Images)

Trump went on to host the second season of "The Apprentice", but not because Zucker agreed to pay $6 million per episode. Setoodeh details that much of Trump's massive windfall from NBC actually came from a deal he made with the show's executive producer Mark Burnett, who agreed to split product placement revenue 50/50. 

Years later, Zucker would become CNN's high-powered president and CEO, something Trump repeatedly took credit for in his conversations with Setoodeh, who in his book notes "Insiders at CNN deny Trump had anything to do with Zucker’s hiring."

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But when Trump first launched his presidential campaign, Setoodeh wrote how the candidate "would often ring up his old boss for gossip and guidance" and how their warm friendship would soon get icy as 2016 unfolded.

"Trump’s and Zucker’s intertwined professional lives came to imitate the art they’d made together. Once inseparable in their shared quest for ratings, the two men—still in search of the highest possible number, be it viewers or electoral votes—found themselves squabbling like reality TV contestants once Trump began sweeping primaries," Setoodeh told readers. 

"For any observer schooled in the tropes of the genre, this wasn’t a surprise. Zucker and Trump’s alliance worked for them when they both stood to profit. Using Trump as a free publicity machine and indulging his tendency to say whatever popped into his mind benefited Zucker and NBC. Yet in this new phase of Zucker’s career, Zucker could no longer protect Trump," he added. 

"CNN’s coverage would inevitably get tougher as Trump closed in on the Republican nomination. And as the network started fact-checking his lies in real time, Trump felt that Zucker had betrayed him."

Jeff Zucker and Donald Trump

The longstanding friendship between Jeff Zucker and Donald Trump became more intense when CNN began covering the GOP candidate more negatively.  (Getty Images)

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Recapping his conversations with Trump, Setoodeh writes as he's quoting the former president "'When I was running, I said, ‘CNN is going to treat me great.’ It’s called loyalty. I got the guy the job. And as I was campaigning, people would come and say, ‘Sir, CNN is hitting you a little hard!’ I would say, ‘That’s not possible. Go back and check.’ And I’d call Jeff.' Trump imitates Zucker’s voice, adding a parodic layer of prissiness: 'I’ll look into that. I’ll look into that." Trump says he finally lost patience and stopped talking to Zucker, because he realized Zucker was secretly driving the tough reporting about his campaign."

In another excerpt, Setoodeh quotes Trump "'I always said there’s no way he’s doing bad about me, and he did. Because a lot of people are scum.' Trump pauses, as if he were about to conduct a firing. But the only power he has away from the Oval Office is the familiar intensity of his venomous contempt, now directed at Jeff Zucker. ‘He’s human scum.’"

A spokesperson for Zucker did not respond to Fox News Digital's request for comment. Zucker declined to comment to Setoodeh.