John A. Farrell, a Nixon biographer, said most other presidents managed to contain or disguise their paranoid elements, but it drove Johnson and Nixon to extremes that were ultimately self-destructive. Mr. Trump, he said, sees no need to hide it.
“He has responded to criticism, opposition and other curbs on his power with a vulgar energy and the vile Nixonian strategy that making Americans hate each other is a potent way to seize and secure power,” Mr. Farrell said. “It is no accident that a president acting this way comes from a chain of influences that includes Roy Cohn and Roger Stone.”
Mr. Trump’s advisers and defenders turn to the old nostrum — just because he may be paranoid does not mean people are not out to get him. The relentless investigations against him, the trash-talking text messages by F.B.I. officials, the excesses of the surveillance warrant on a former campaign adviser, the longtime lawyer-fixer who turned against him, the whistle-blower who took his concerns to House Democrats, all of it, they said, has contributed to an understandable defensiveness.
“Trump came to office with an almost pathological distrust of others and an irresistible impulse to attack any perceived threat,” said Jonathan Turley, a law professor at George Washington University who testified against impeachment last year before the House Judiciary Committee. “The well-documented bias in the F.B.I. and Justice Department against Trump fuels his suspicions and tendency to counterpunch. Both his perceptions and his responses became more exaggerated.
“However,” Mr. Turley added, “his suspicions were validated to some degree in these investigations — something that many refuse to acknowledge. He came to Washington with an agenda that was highly antagonistic and threatening to the status quo. It was immediately clear that he faced deep opposition to his agenda.”
As with so many aspects of his personality, the seeds of Mr. Trump’s reaction may lie in his biography. Michael D’Antonio, the author of “The Truth About Trump,” recalled that the future president was raised by a father who taught him that all of life is a battle for power and that he should be a “killer.” Mr. Trump, Mr. D’Antonio said, came to see others as useful for his own purposes or obstacles to be crushed.
“In this way, he’s forcing us all to live in the world that once existed only in Trump’s mind and in his close circle,” Mr. D’Antonio said. “Here, in Trump’s America, we’re to believe that all institutions are corrupt. No one is to be trusted. Those who would speak against him hesitate. Words of protest and revelations that might be made by whistle-blowers are stifled by fear. This is the world Trump has always inhabited and he wants us to live there too.”
Peter Baker reported from Washington, and Maggie Haberman from New York.