“Watergate pales, really, in my view, compared to what we’re confronting now,” James R. Clapper Jr., the former director of national intelligence, has said. David Corn, an author of “Russian Roulette,” a book about the case, has described it as “much bigger than what happened in Watergate.” After Mr. Comey’s dismissal, James Fallows wrote in The Atlantic that “this scandal looks worse than Watergate.” Carl Bernstein, one of the Washington Post journalists who led the coverage of the Nixon scandal, has said this appears “worse than Watergate in many, many ways.”

Like Hillary Clinton and the “vast right wing conspiracy,” Mr. Trump and his allies are trying to focus attention on the conduct of their pursuers, arguing that the F.B.I. or the special counsel investigating Russia’s involvement in the election have themselves stepped over the line. The president’s tweet on Thursday seized on a column in a conservative magazine asserting that the F.B.I. most likely had a confidential informant inside Mr. Trump’s campaign in 2016…

“Our sources are telling us that the abuse of power is far bigger than Watergate,” Sean Hannity, the Fox News host and friend of Mr. Trump’s, said in January. “I have long said it is worse than Watergate,” agreed Representative Steve King, Republican of Iowa.