Roger Stone thinks the Russia investigation may be the end of President Trump.

So he may as well write about it, just in case.

The Trump confidant and former campaign adviser told Vanity Fair that he's working on a book entitled The Fall of Trump, part of a multi-book deal he already has. The idea was born from watching how the White House has responded to special counsel Robert Mueller's investigation into Russia's interference in the election and possible collusion with the Trump campaign.

"It's painfully obvious Mueller will bring charges," Stone said. "The theory is Mueller will indict him on some-process related matter...The only people who don't seem to know it are Ty Cobb, (John) Dowd and the president." (Cobb and Dowd are Trump's lawyers in the probe.)

Stone said he's been working on the book "as we go along."

Still, he insisted that he doesn't want Trump to fall. He's merely covering his bases.

"I hope it's a book I don't have to publish," he said. "I just don't think Trump is being told the truth about how bad things are."

While Mueller's probe has resulted in the prosecutions of four Trump aides – including former national security adviser Michael Flynn and ex-campaign manager Paul Manafort – Stone himself has not yet been charged or accused of anything by any of the congressional committees conducting their own Russia probes.

The flamboyant political operative testified in September before the House Intelligence Committee behind closed doors. Lawmakers quizzed him about his advance knowledge of the release of a tranche of embarrassing emails from the account of Hillary Clinton campaign chief John Podesta by WikiLeaks during the heat of the 2016 campaign.

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