Thomas Jefferson lamented the "putrid state" of newspapers in a letter to a friend. Franklin Roosevelt declared that 85 per cent of the press was opposed to his agenda. Richard Nixon privately fumed that the media were "the enemy."

Nearly every U.S. president has complained about the press. But none has disparaged the media quite like Donald Trump.

Consider the past week: Mr. Trump assailed television host Mika Brzezinski ("dumb as a rock," in his words, and "bleeding badly" from a face lift), called the media "FAKE AND FRAUDULENT" and tweeted a video clip doctored by a supporter to show Mr. Trump triumphantly punching and knocking down the CNN logo.

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While presidents have long had bitter and contentious relationships with the press, Mr. Trump is ushering in an era of hostility remarkable for the willingness of the President himself to deliver a steady stream of tabloid insults.

Media historians also said they could not recall a president ever alluding to violence in retaliation for coverage of his administration, as Mr. Trump appeared to do by sharing the video of him pummelling CNN.

(The closest parallel they could cite was Harry Truman once writing a letter to a music critic who had criticized a performance by his daughter, describing his desire to punch the critic.)

For all of Mr. Trump's loud criticism on Twitter and elsewhere, his assault against the media has remained in the realm of rhetoric, historians noted. Some presidents have gone further: Mr. Nixon was far more subdued than Mr. Trump in public but privately used the powers of his office to "pursue, harass and intimidate journalists," said Michael Schudson, an expert on the history of the American media at Columbia University. Mr. Trump "is – I hate to say this – a lot of bark and no bite."

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Still, Mr. Trump's words work to delegitimize the news media and cultivate resentment of journalists, particularly among his supporters. They also act as a powerful signal in today's polarized political environment, turning one's view of the media into yet another partisan litmus test. A poll conducted over the weekend by Survey Monkey found 89 per cent of Republicans viewed Mr. Trump as more trustworthy than CNN. For Democrats, however, it was the inverse: 91 per cent said CNN was more trustworthy.

By constantly calling the media "fake news," Mr. Trump is not saying "they've got this wrong, they're unfair to me," said David Greenberg, a media historian at Rutgers University. "He's trying to suggest that the whole thing is just manufactured and made up. That goes beyond where other presidents have gone."

Experts stressed that there are plenty of bad chapters in the long history of the relationship between U.S. presidents and the media. In the country's early years, John Adams signed a series of laws known as the Alien and Sedition Acts, which were used to throw journalists in jail. During the First World War, Woodrow Wilson enacted legislation that made criticism of the government and its war effort a crime.

The first American newspapers were offshoots of political parties, with openly partisan aims. At times, that led to vicious criticism of presidents and leading political figures (in 1797, a Boston newspaper published a poem devoted to Alexander Hamilton, the former treasury secretary, calling him a "monster" and a "slave to lust"). It was not until the 20th century that an independent-minded media developed a Washington press corps devoted to covering the president.

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Historians say the modern nadir for presidential treatment of the press came under Mr. Nixon. Mark Feldstein, a professor of journalism at the University of Maryland and the author of a book on the Nixon years, noted the administration wire-tapped journalists, put them on "enemies" lists, audited their tax returns and used the levers of government to retaliate against media companies. Two presidential aides even developed a plot – later dropped – to assassinate an investigative journalist Mr. Nixon detested.

"At that point, there had never been quite such a systematic assault on the news media as an institution," Prof. Feldstein said. Mr. Nixon was "sneakier" than Mr. Trump, he added, often remaining in the background while his surrogates berated the press in public. Whether Mr. Trump translates words into actions, however, remains to be seen. Mr. Trump "hasn't had much time yet to sink his teeth into the news media in terms of policy and I think he will try it," Prof. Feldstein said.

Mr. Trump is not the first president to view media-bashing as a winning technique for galvanizing his supporters. Mr. Nixon did, too, and, to a lesser extent, so did Mr. Roosevelt. Andie Tucher, a historian at Columbia University's School of Journalism, noted that while Mr. Roosevelt was admired by individual journalists, he had a tense relationship with media barons, some of whom opposed his New Deal reforms (when Mr. Roosevelt was up for re-election in 1936, the publisher of the Chicago Tribune instructed receptionists to answer the phone saying that only days remained to "save the American way of life").

While the current climate of hostility between the President and the press ranks high on the historical scale, it is not so much the bitterness that distinguishes today's environment, Prof. Tucher said, but rather its daily intensity. Thanks to Twitter, Mr. Trump can issue his critiques instantly, which in turn prompts instantaneous responses and "an endless hamster wheel" of commentary.