By Christian Holub
Updated July 18, 2016 at 05:01 PM EDT
Steve Sands/WireImage

Most Americans were first introduced to Donald Trump through his 1987 memoir, The Art of the Deal. The book was a breakthrough success, spending 48 weeks on the New York Times best-seller list and painting Trump as a charming businessman with good instincts. Trump has referenced the book in stump speeches over the course of his presidential campaign, much to the dismay of The Art of the Deal ghostwriter Tony Schwartz. Recently, however, Schwartz has become vocal about his opposition to Trump’s campaign, giving explosive interviews to The New Yorker and Good Morning America.

“I put lipstick on a pig,” Schwartz told The New Yorker. “I feel a deep sense of remorse that I contributed to presenting Trump in a way that brought him wider attention and made him more appealing than he is. I genuinely believe that if Trump wins and gets the nuclear codes there is an excellent possibility it will lead to the end of civilization.”

Schwartz added that if he were writing The Art of the Deal now, he would call it The Sociopath. On Monday, Schwartz clarified his comments on Good Morning America, explaining how a President Trump could very well lead to an end of civilization.

“I haven’t slept a night since Donald Trump announced his bid for president,” Schwartz said. “I believe he is so insecure, so easily provoked, and not particularly nearly as smart as people might imagine he is. In the face of someone like Putin provoking him cleverly, cause Putin’s a heck of a lot smarter than Donald Trump, I do worry that he with the nuclear codes he would end civilization as we know it.”

Watch the video below.