In “The Plot Against America,” the novelist Philip Roth imagines an alternative history at the dawn of World War II. Charles A. Lindbergh, aviator hero and crypto-fascist, defeats Franklin D. Roosevelt in 1940. Rather than go to war against Nazi Germany, he foments an atmosphere of hatred directed at Jews in the United States.

President Lindbergh’s rule is based on fear. He can violate the Constitution because enough Americans do not mind limiting the freedom of a suspect minority in the name of security.

Of course, it could never happen here. It’s a novel, silly boy — one of late-stage Roth’s better efforts. Made-up stuff. That’s what I’ve always thought. But over the last three months, in listening to plans of the Republican presidential front-runner and the views of his increasingly thuggish followers, I’m starting to have some dark fears should Donald Trump become president.

Take him at his word — albeit, a worthless thing given his propensity for telling outright lies and not backing down when called on them — Donald Trump’s reign would be a police state. He has now outlined a series of measures that would make the United States an authoritarian nightmare. Trump is no longer entertaining, or diversionary. He’s a billionaire brute, his bluster getting more ominous by the day.