In the 768-page tome, entitled "A Promised Land" and out on November 17, Obama flashes back on his political career but admits in the personal, revealing life in the White House grew his smoking habit and caused tension in his relationship with his wife, Michelle.
"It was as if my very presence in the White House had triggered a deep-seated panic, a sense that the natural order had been disrupted," Obama writes in the book.
"Which is exactly what Donald Trump understood when he started pedaling assertions that I had not been born in the United States and was thus an illegitimate president. For millions of Americans spooked by a Black man in the White House, he promised an elixir for their racial anxiety," he writes.
Yet, Obama argues, the origins of the problem came before the current president. He traced it to John McCain's decision to name Alaska Gov. Sarah Palin as his running mate in the 2008 presidential election.
"Through Palin, it seemed as if the dark spirits that had long been lurking on the edges of the modern Republican Party -- xenophobia, anti intellectualism, paranoid conspiracy theories, an antipathy toward Black and brown folks -- were finding their way to center stage," Obama writes.
Nonetheless, he goes on to clear McCain of any obligation, saying he believed the senator, who died of brain cancer in 2018, wouldn't have made the same choice if he knew what the future held.
"I'd like to think that given the chance to do it over again, he might have chosen differently," wrote Obama, who gave one of the tributes at McCain's funeral. "I believe he really did put his country first."