Firing the FBI director leading the investigation into his campaign’s possible collusion with an adversarial foreign power is big stuff, the biggest shock President Donald Trump has delivered in his short, shock-filled presidency.

“It really does have the smell of Watergate,” says historian Robert Dallek. “It just raises suspicion this is a Nixonian president trying to cut off this investigation or at least delay it.”

The potential is there to find evidence of collusion that could be termed traitorous, says Dallek. “If he were so clean and without any kind of compromise in this situation, he’d let the investigation go forward and urge a special prosecutor to take over. Instead, he’s giving every sign of a coverup.”

The letter Trump sent to FBI Director James Comey said, in effect, “thanks for exonerating me” three times (like so many Trump claims, the only sign it’s so is that Trump said it)—and then fired him. But Trump can’t abolish the position, and whoever he appoints will have to be vetted and confirmed by the Senate.

Maybe Trump and his coterie of yes-men ignorant of history think he can name a loyalist. “Then the question is will the Senate bend a knee to him?” says Dallek. Democrats will resist, and already some Republicans, including Jeff Flake and Lindsey Graham, indicated that they too would resist the wrong pick.

Most strange is the Trump administration’s reaction to the firestorm set off by the firing—it took hours for the White House to even dispatch surrogates, after first insisting that the letters from Attorney General Jeff Sessions and the deputy attorney general, Rod J. Rosenstein, calling for Comey’s ouster spoke for themselves—that revealed their tone-deafness and their ignorance of history.

“This is not fake news, this is real news, and it evokes historical memories in a lot of people in Washington who remember what happened in 1974,” says Dallek. “That’s not 200 years ago.”

Actually it was October of 1973 when Nixon fired two attorney generals, one after the other, first Elliot Richardson and then his deputy William Ruckelshaus, when they refused to fire Special Prosecutor Archibald Cox, who was looking into Watergate. They finally found someone who would do it, then-Solicitor General Robert Bork, who would gain fame in the ’80s for his failed Supreme Court nomination.

Nixon speechwriter and adviser Patrick J. Buchanan was in the Oval Office with Nixon when a deal was struck for Richardson to accept summaries of the incriminating tapes Nixon had made, as opposed to the tapes themselves. But Cox wouldn’t accept the deal, and Richardson wouldn’t fire him—so Nixon did, setting off what was dubbed the Saturday Night Massacre.

When I reached Buchanan on the phone, he said, “Déjà vu all over again,” deeming Trump’s firing of Comey the Tuesday Night Massacre. He was in New York launching his new book on the Nixon White House with a full chapter on the original Saturday night one. That was such an enormous firestorm that by Monday the Office of the Special Counsel was reconstituted and Leon Jaworski named to the position. He prosecuted the case that forced Nixon’s resignation in August 1974.

While nodding to the similarities, Buchanan judged that “this is not comparable at all,” making the point that no evidence of collusion has thus far been found, and that a new FBI director will take over.

“This too shall pass,” he said, unlike October 1973, when he says, “I knew in my bones,” that it was over. He told friends that same night that Articles of Impeachment would be introduced in the House the following Tuesday, and he was right.

For those dizzied by the events in the Trump presidency, Buchanan notes that earlier in the month of the Saturday Night Massacre, Vice President Spiro Agnew had resigned and Gerald Ford had been named to the vice presidency. And the Yom Kippur War was raging.

“We weren’t sure the republic would survive,” says Democratic political strategist Les Francis, who was working then for a teachers union in California. “We didn’t know what Nixon would do if he was pushed to the wall.”

Defense Secretary James Schlesinger alerted people in the Pentagon they shouldn’t necessarily obey the president. Buchanan reconstitutes in his book the commentary of the times. NBC’s John Chancellor called it America’s greatest constitutional crisis—neglecting to include the Civil War. Others speculated the Army would be coming out, though they weren’t sure which side it would be on. There’s a whiff of Gestapo in the air, opined another.

Forty years later, the Nixon Library has remodeled its exhibits to put the president in a better place for new generations. They remind young people Nixon was more than Watergate. He created the Environmental Protection Agency, for example, and the library is keeping their social-media current. They want us to stop comparing Trump to Nixon, tweeting after Comey’s firing this “Fun Fact: President Nixon never fired the Director of the FBI.”

President Nixon never starred in a reality show where he could fire anyone he wanted. President Trump, still in his first four months, is testing the limits of his contract with the American people.