When JD Vance spoke at the Richard M Nixon presidential library last week about his new book on his journey from atheism to an allegedly devout Catholicism, he raised eyebrows by minimizing Watergate. “The idea that it [took] down a presidency is crazy,” he said. He said it was the “deep state that took down Richard Nixon”– not the 37th president’s implication in serious crimes.

Commentators were shocked. Did the vice-president not know that the investigation proved Nixon directed a conspiracy to bribe the men who broke into the Democratic party headquarters to lie in court from a secret, illegal slush fund?

That, when the president’s lawyer John Dean tried to warn him away from the attempt by suggesting it would take a million dollars that they would have to launder – “this is the sort of thing mafia people can do” – Nixon reassured him that the mafia had nothing on him: “You could get it in cash. I know where it could be gotten.”

Vance’s blithe avowal was said by commenters in my country to represent a new low in Republican cynicism. Was this the sort of thing they now think presidents should get away with?

My fellow Americans: you have memories like goldfish. Republicans have always said that – ever since Nixon’s first speech on Watergate in April 1973 about the botched burglary that set the scandal in motion 10 months earlier, when a prominent ally said it was just a prank at a press conference the next day, that the break-in was part of the “usual atmosphere of campaigning”, and the culprits were “not criminals at heart”.

That Republican ally was the governor of California, Ronald Reagan, speaking at a reception for visiting group of students. The media mocked him. The New York Times columnist Tom Wicker was enraged at how an “exponent of law and order” had surrendered to the philosophy that “[s]afeguards that ‘we’ support and revere in ordinary times must be suspended or limited for the duration – but only for ‘them’. ‘We’ will not be safe until ‘we’ crack down on ‘them’, occasionally by adopting their tactics.”

Reagan did not listen. After it was revealed that Nixon secretly taped many of the people he met, he called the investigation a “witch-hunt” and a “lynching”. After Nixon gave a speech insisting there wasn’t even anything to cover up, only 25% of Americans believed him. But Reagan called it “the voice of reason”.

At that, Reagan’s own anguished political aides had enough. They leaked to columnists their anguish that efforts to promote him for the presidency as “the successful architect of clean, frugal government, free of scandal” were being stymied by their boss’s insistence in treating the conspirators as “no worse than double parkers”. But they were wrong.

In my 2014 book, The Invisible Bridge: The Fall of Nixon and the Rise of Reagan, I demonstrate it was precisely Reagan’s ability to rhetorically absolve his fellow Republicans of sin, in supporting the Nixon of Watergate, that made him so attractive to the conservative rank and file as a party standard bearer – so much so that he came shockingly close to defeating incumbent Gerald Ford for the party’s presidential nomination in 1976.

And that same mystic ability to affirm Americans’ sense of their own unimpeachable innocence, even if they had supported crimes – such as Watergate or Vietnam – eventually made him president.

Reagan was hardly the only figure to rise in the Republican firmament this way. One Nixon White House aide, Pat Buchanan, testified to the Senate investigating committee that its very investigation was merely politics by other means: the liberal Washington establishment working to steal back the White House after Nixon won it fair and square with his 1972 landslide.

He was rewarded for his candor with a widely syndicated column, becoming such a conservative hero that in 1992 he made a shockingly strong showing as a candidate in the 1992 New Hampshire primary against George HW Bush – himself something of a professional Watergate minimizer in his role back then as RNC chair.

A steady stream of books spin conspiracies that anyone but the president’s men were behind it: that it was the CIA (Jim Hougan, Secret Agenda, 1984); or a Silent Coup (Len Colodny and Robert Gettlin, 1992) executed by Dean himself to hide a prostitution ring run by his wife, or The Secret Plot to Make Ted Kennedy President (Geoff Shepard, former Nixon White House aide, 2008).

Shepard then published two more tomes elaborating his version of the plot, in 2015 and 2021, then wrapped them up in a 2024 documentary that’s proven highly influential in the young Maga circles in which JD Vance moves.

A book called It Didn’t Start With Watergate, in 1977, dubiously elevated a number of peccadilloes from past Democratic presidents to a Nixonian level of equivalency, and even claimed Democratic party foreknowledge – and indifference – to the 1972 burglary.

It proved so influential that the phrase “everyone did it, Nixon got caught” became an American commonplace; I myself used to hear it all the time from my not particularly political dad.

Though perhaps the most influential contributor to the minimization discourse assiduously deployed sophisticate public relations techniques of misdirection – which was William Safire’s profession, before he became a Nixon White House speechwriter and then a widely syndicated New York Times columnist, where he invented the technique of affixing the suffix -gate to a series of conspicuously sub-Watergate scandals involving Democrats, from “Vancegate”, to “Koreagate”, to “Billygate”, to “Monicagate”.

Everyone does it – a damned good thing, too, more brazen Republicans avowed, at least when it’s the right people doing it. “I didn’t like Nixon until Watergate,” intoned a legendary conservative movement activist, M Stanton Evans (whose specialty was training conservative journalists) at a conference during George W Bush’s presidency after I presented a litany of Republican rule-breaking to make the argument that Watergate might be considered, in fact, one of the essences of American rightwing politics.

That proved my point: he meant that Watergate was what finally convinced him that Nixon, an ideological non-conservative he had not previously trusted, finally understood that, yes, “we” will not be safe until “we” crack down on “them”.

Which, of course, is the spirit behind almost everything that comes out of Donald Trump’s mouth these days. As for his No 2 man, Vance also said, in the Yorba Linda, California, mausoleum in which Nixon’s political spirit is preserved for tourists: “If Watergate happened tomorrow, it would be like a 12-hour news story.” One reason he is probably correct is precisely that unbroken lineage of Watergate propaganda he has just joined.

• Rick Perlstein is an American historian and the author of Nixonland and The Invisible Bridge: The Fall of Nixon and the Rise of Reagan