To hear Max Boot tell it, he feels as forlorn as the despondent, battered elephant on the cover of his new book, “The Corrosion of Conservatism: Why I Left the Right.” Boot minutely describes a disillusionment that wasn’t only “painful and prolonged” but “existential.” Here he is — a lifelong Republican with sterling neoconservative credentials (an enthusiastic supporter of the Iraq War and a champion of “American empire”) — explaining why he’s eager for the day when “the G.O.P. as currently constituted is burned to the ground.”

The scorched-earth rhetoric reflects not just a pro-war pedigree but also a profound feeling of betrayal. In the run-up to the November 2016 election, Boot was a vocal Never Trump conservative who couldn’t fathom that a “crudely xenophobic” reality television star would become the standard-bearer of the Grand Old Party, much less president of the United States. Along with Nebraska Sen. Ben Sasse’s “Them: Why We Hate Each Other — and How to Heal,” another new volume by a Republican critic of Trump, Boot’s book attempts to answer a looming question for conservatives unhappy with the current occupant of the White House: What now?

“The Corrosion of Conservatism” does double duty as a mea culpa memoir and a political manifesto, detailing Boot’s “heartbreaking divorce” from the Republican Party after decades of unstinting loyalty. He charts a political trajectory that gave his life social and emotional meaning. As the 6-year-old son of Jewish refuseniks, Boot emigrated from the Soviet Union in 1976; at 13, he was inducted by his father into the world of “learned, worldly, elitist” conservatism with a gift subscription to National Review.

Image Max Boot Credit... Don Pollard

Years later, even amid the peer pressure of “Berzerkeley,” the young Republican persisted. He may have been a white man of some means, but he enjoyed seeing himself as a besieged minority. He “loved making a bonfire” of Berkeley’s “liberal pieties” in his column in the student newspaper and trolling his peers with a “Bush-Quayle ’88” sticker on his dorm-room door. He swiftly clambered up the echelons of the conservative establishment, editing the op-ed page of The Wall Street Journal by the time he was 28 and eventually advising the presidential campaigns of John McCain, Mitt Romney and Marco Rubio.