From Why Donald Tump Is Giving John Dean Nightmares (typo in the original title):
Few people are more intimately acquainted than Dean with the consequences of an American presidency gone awry. As White House counsel under President Richard Nixon from 1970 to 1973, he was a key figure in the Watergate saga—participating in, and then helping to expose, the most iconic political scandal in modern U.S. history. In the decades since then, Dean has parlayed that resume line into something of a franchise, penning several books and countless columns on the theme of presidential abuses of power....
Dean’s near-panicked take on the incoming president is shaped in large part by his years in the Nixon White House. In Trump, Dean says he has observed many of his former boss’s most dangerous traits—obsessive vengefulness, reflexive dishonesty, all-consuming ambition—but none of Nixon’s redeeming qualities.
“I used to have one-on-one conversations with [Nixon] where I’d see him checking his more authoritarian tendencies,” Dean recalled. “He’d say, ‘This is something I can’t say out loud...’ or, ‘That is something the president can’t do.’” To Dean, these moments suggested a functioning sense of shame in Nixon, something he was forced to wrestle with in his quest for power. Trump, by contrast, appears to Dean unmolested by any such struggle.