Sean Spicer's new book details his time with Trump's campaign and presidency, in an attempt to set the "record straight."
In "The Briefing: Politics, the Press and the President," the former White House press secretary repeatedly praises Trump and calls him a "unicorn, riding a unicorn over the rainbow."
He admits that Paul Manafort was key to the Trump campaign, refuting his previous claims that Manafort played a "limited" role.
Spicer also claims that his handling of the debate over Trump's inauguration crowd size was the "the beginning of the end" of his time as press secretary.
Sean Spicer has written a book detailing his time working for Donald Trump, and described the president as "a unicorn, riding a unicorn over a rainbow."
In "The Briefing: Politics, the Press and the President," the former White House press secretary wrote:
"I don’t think we will ever again see a candidate like Donald Trump. His high-wire act is one that few could ever follow. He is a unicorn, riding a unicorn over a rainbow.
"His verbal bluntness involves risks that few candidates would dare take. His ability to pivot from a seemingly career-ending moment to a furious assault on his opponents is a talent few politicians can muster."
Spicer resigned last July after six months on the job, but has remained a vocal fan of Trump.
RELATED: Sean Spicer's most controversial moments as Trump's press secretary (BI)
Spicer admits Manafort's role in the campaign
In the book, Spicer also admitted that Paul Manafort, who is the focus of Robert Mueller's investigation into the Trump campaign's ties to Russia, played a central role in the Trump campaign — refuting his previous claims that Manafort only had a "limited role" for a "limited time" in the campaign.
Spicer said in the book:
"Paul brought a much-needed maturity to the Trump campaign when it needed an experienced political professional operative more than anything else.
"There was no semblance of a campaign structure, just a few, distraught, overworked people constantly barking into their phones. Paul immediately set up and staffed the political and communications operations necessary to take on the Clinton machine.
"The Manafort message was clear: Trump will be our nominee and our next president, and anyone who didn't want to work to that end could spend the next four years in political Siberia. (No Russia pun intended.)"
'The beginning of the end'
In the book, Spicer also claimed that Trump was unhappy with the way he handled the debate over the inauguration crowd size with reporters — which marked "the beginning of the end" of his role as press secretary.
"This was the largest audience to ever witness an inauguration, period, both in-person and around the globe," the then-press secretary claimed last January, contrary to the numerous photos taken of the National Mall on Friday that appeared to show a smaller audience than the crowd at former President Barack Obama’s 2009 inauguration.
Spicer assumed Trump wanted him to be "strong, aggressive, no questions," he said in the book. Instead, Trump was angry that he did not take questions and that Spicer did not run his statement by him.
"I went back to my office, expecting an 'attaboy' from the president; instead Reince was waiting for me and said the president wasn’t happy at all with how I had performed. ...
"Minutes later, the president himself called, and he was not pleased. And I started to wonder if my first day would be my last. ...
"I had made a bad first impression, and looking back, that was the beginning of the end."
Spicer has sought to remain in the spotlight after his departure from the White House. He is planning to host a TV show that would have him talk to interesting guests, and he also recently started a podcast with the Fox News contributor Katie Pavlich.