The ghostwriter of "The Art of the Deal" thinks President Donald Trump will resign before the end of the year.

Tony Schwartz, who spent 18 months working with Trump on the best-selling book, believes the president will step down and "declare victory" before special counsel Robert Mueller and Congress “leave him no choice.”

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On CNN's "Anderson Cooper: 360," Schwartz said the ongoing investigation into alleged collusion between the Trump campaign and Russia, in addition to the president's much-criticized response to the violence in Charlottesville and his tough rhetoric on North Korea, will force him to "figure out a way to resign."

"I think the snowball is beginning to gather momentum as it comes down the mountain,” Schwartz said. “It reminds me a lot of Watergate and the last days of Nixon. When the tide turns, it really turns, and that’s what happened here."

He argued that Trump is self-destructive and has put himself in a no-win position, and he wants to find a way out while saving face.

"He's going to blame it on the Democrats. He’s going to actually blame it on the Republicans," Schwartz said. "He’s going to blame it on anybody he can, and he’s going to say that he did everything he could to save America.”

Watch the interview below.

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