This is more than the biography of a single bully, although that’s how I envisioned it at first.

A uniquely American strain of demagoguery has pulsed through the nation’s veins since its founding days. While Senator Joe McCarthy’s drastic tactics and ethical indifference make him an extraordinary case, he was hardly an original. Rather, he owed much to a lineup of zealots and dodgers who preceded him—Huey “the Kingfish” Long, Boston’s “Rascal King” mayor James Michael Curley, and Michigan’s Jew-baiting radio preacher Father Charles Coughlin, to name a few—and McCarthy, in turn, became the exemplar for the bullies who followed.

Now that we at last have access to the full sweep of records on McCarthy’s transgressions—his widow donated the archives 60 years ago to his alma mater, Marquette University, and they were made available, for the first time, to this author—we can see that his rise and reign also go a long way toward explaining the astonishing ascension of President Trump. While some seek comfort in the belief that Trump’s election was an aberration, the truth is that he is the latest in a bipartisan queue of fanatics and hate-peddlers. In lieu of solutions, demagogues point fingers. Attacked, they aim a wrecking ball at their assailants. When one charge against a manufactured enemy is exposed as hollow, they lob a fresh bombshell. If the news is bad, they blame the newsmen. McCarthy was neither the first nor the last, but he was the archetype, and Trump owes much to his playbook.

Demagogue’s Game

The playbook, invariably, is the key. It transformed McCarthy from a crank to one of the most menacing men in modern civilization. Armed with a similar blueprint, Trump rose from sideshow to contender to commander in chief. Neither was sure of the formula in advance—bullies seldom are, but they can sense in their bones how to keep the pot simmering. As a presidential candidate in 2016, Trump famously boasted to supporters that “I could stand in the middle of Fifth Avenue and shoot somebody, and I wouldn’t lose any voters.” Sixty-two years before, polling pioneer George Gallup wrote a similar prediction about Joe’s minions: “Even if it were known that McCarthy had killed five innocent children, they would probably still go along with him.”

At the time when McCarthy drafted his poisonous script, few people knew the Wisconsin native’s full story. America got its best look at the single-minded senator in his public and prodigiously publicized hearings, when he targeted alleged Soviet infiltration of the Foreign Service and then, in a step too far, the mighty U.S. military. “Have you no sense of decency, sir, at long last?” the army’s special counsel famously asked him on live television in the spring of 1954, echoing what much of the nation was thinking by then. Americans would have asked a lot sooner, and reached a quicker tipping point, if they had witnessed the secret hearings McCarthy was holding. It turns out that only about a third of his conspiracy hunting happened in public session; evidence of the rest, filling almost 9,000 pages of transcripts, was kept under lock and key for more than half a century.

America got its best look at the senator in his public and prodigiously publicized hearings.

Those records reveal in disturbing detail that when the subcommittee doors slammed shut, Chairman McCarthy became unhinged in a way unimaginable to most Americans. He ceased even pretending to care about the rights of the accused, whom he summarily declared guilty. He held one-man hearings, in violation of Senate tradition. And he grew nastier still after lunch, where he routinely washed down his hamburger and raw onion with whiskey. Here, in executive session, when he thought nobody was looking, this snarling senator showed his unvarnished essence.

When the subcommittee doors slammed shut, Chairman McCarthy became unhinged.

If that is the darker-than-we-knew side of McCarthy, there is also an untold tale of the beguiling charm with which he seduced the Badger State and much of America. Snippets of the private Joe—the relentless yet riveting sycophant, incongruously generous to those he had just publicly upbraided—have filtered out over the decades, but generally from unreliable sources bent on shielding or savaging the senator. Now we have his unscripted writings and correspondence, military records and wartime medical charts, love letters, and box after box of other personal and professional documents.

These papers reveal a figure far more layered and counter-intuitive than the two-dimensional demagogue enshrined in history. Just three years before he launched his all-out crusade against Russian-style Communism, McCarthy was taking courses in the Russian language and assuring his instructors they were playing a role “in the furtherance of peace and understanding.” Later, when his Red-baiting was going full-steam and his favorite target was Harvard University—McCarthyites called it “the Kremlin on the Charles”—Joe and his wife, Jean, were troubled by the beating that Harvard physicist Norman Ramsey was taking on Meet the Press, as reporters goaded the professor into defending the university against Joe’s brickbats. As soon as the show was over, the McCarthys invited Ramsey to a dinner party; he came and stayed for three and a half hours while McCarthy charmed him and offered him a job, which he declined. “I’m not sure that we convinced him,” Jean recalled of their evening with the scientist, who, three decades later, would win the Nobel Prize. “But I’m sure he left agreeing that Joe doesn’t have horns.” Ramsey volunteered a different takeaway: “At that time there was some speculation that McCarthy might become president or even a dictator. After our evening together I concluded this was no threat from McCarthy alone but might be with him and his wife together.”

The newly disclosed records let us shave away the myths and understand how the junior senator from Grand Chute rose to become powerful enough not just to intimidate Dwight Eisenhower, our most popular postwar president, but to provoke senators and others to take their own lives. Image often trumped ideology for the senator: an outspoken homophobe, McCarthy allowed two gay people—Roy Cohn and David Schine—to get close to him and ultimately ruin his career. The senator cared more that young Roy was as ruthless as he was, had a spotless record of baiting and bashing Reds, and, most of all, that he was Jewish at a time when McCarthy needed a shield against charges that he was a Jew-hater. There also was speculation, by everyone from the closeted J. Edgar Hoover to the fearless owner of the Las Vegas Sun, Hank Greenspun, that McCarthy, too, was gay. (As for Schine, McCarthy tolerated him because Roy insisted on it.)

McCarthy is revealed as neither the Genghis Khan his enemies depicted nor the Joan of Arc rendered by friends. Somewhere between that saint and sinner lies the real man. He was in fact more insecure than we imagined, more undone by his boozing, more embracing of friends and avenging of foes, and more sinister.

Larry Tye’s Demagogue: The Life and Long Shadow of Senator Joe McCarthy will be published on July 7 by Houghton Mifflin Harcourt