President Donald Trump suggested Wednesday that he might revoke White House credentials for some journalists, following the publication of a survey that showed a dramatic leftward tilt in television news coverage about him.

The Media Research Center, a conservative watchdog group, tracked the evening newscasts on ABC, CBS and NBC for the first four months of this year and found more than 1,600 'explicitly positive and negative' statements about the president.

The group determined that nine out of 10 of those broadcast statements were negative. It did not include CNN and MSNBC in its research.

Trump vented, saying: 'The Fake News is working overtime. Just reported that, despite the tremendous success we are having with the economy & all things else, 91% of the Network News about me is negative (Fake). Why do we work so hard in working with the media when it is corrupt? Take away credentials?'

The president, though, ignored a journalist's question hours later when he was asked before a Cabinet meeting whether or not he would 'ban press from the White House.'

President Donald Trump lashed out Wednesday at the reporters who cover him, saying 91 per cent of coverage of him that the three major TV networks air is negative

'Take away credentials?' Trump asked, suggesting a heavy-handed approach to press freedom

The Media Research Center found a massive disparity on ABC, CBS and NBC between positive and negative coverage of key issues since Trump became president

Hours after he tweeted, Trump ignored a journalist's question about whether or not he would 'ban press from the White House'

White House Correspondents Association president Margaret Talev, who covers the Trump administration for Bloomberg Politics, said that 'a president preventing a free and independent press from covering the workings of our republic would be an unconscionable assault on the First Amendment'

The White House Correspondents Association, a group whose membership includes most of the Reporters who work at 1600 Pennsylvania Avenue, pushed back hard against the idea of restricting access to the White House.

'Some may excuse the president’s inflammatory rhetoric about the media, but just because the president does not like news coverage does not make it fake,' Margaret Talev, the organization's president, said in a statement.

'A free press must be able to report on the good, the bad, the momentous and the mundane, without fear or favor. And a president preventing a free and independent press from covering the workings of our republic would be an unconscionable assault on the First Amendment.'

The Media Research Center, which regularly blasts out signs of media bias on its 'Newsbusters' website, reported the '91%' statistic cited by Trump when it analyzed network news coverage in September, October and November.

Internet news distribution pioneer Matt Drudge said he's concerned the president might be headed toward licensing all journalists

Harvard University Kennedy School of Government's Shorenstein Center, no conservative lapdog, released a broader report after Trump's first 100 days in office and found a similar result.

It analyzed all coverage of Trump in the print editions of The New York Times, The Wall Street Journal and The Washington Post; the main newscasts of CBS, CNN, Fox News, and NBC; and a trio of European outlets that included The UK’s Financial Times and BBC, and Germany’s ARD.

The result: Fully 80 per cent of non-'neutral' coverage about Trump was negative, and just 20 per cent was positive.

CNN, NBC and CBS – in that order – aired the least positive news about the president, each of them registering in the single-digit percentages.

Trump has long been a critic of the White House press corps' coverage of him, branding some 'fake news' outlets 'the enemy of the American people' and saving his harshest criticism for The New York Times and CNN.

Drudge also pointed out that Democrats in the U.S. Senate had suggested licenses for reporters in the past

'The Fake News is working overtime' to attack him, the president fumed Wednesday

Harvard's Shorenstein Center at the Kennedy School of Government found last year that during Trump's first 100 days in office, negative coverage of him outstripped positive coverage by a 4-to-1 margin

Matt Drudge, the Internet publisher behind the influential Drudge Report website, posted a rare personal tweet on Wednesday morning to warn about what might follow from the White House.

'I fear the future result of Trump’s crusade on "fake news" will be licensing of all reporters,' Drudge wrote, noting that Democrats 'already floated this in the senate pre-Trump.'

'The mop up on this issue is going to be excruciating,' he predicted.

In 2013, California Democratic Sen. Dianne Feinstein proposed amending a media 'shield' law considered by Congress in order to declare that only 'paid' journalists should be protected.

The U.S. Constitution's First Amendment says that the federal government cannot take any action 'abridging the freedom of speech, or of the press.'

Feinstein said at the time that she wouldn't 'support it if everyone who has a blog has a special privilege.'

The president has taken his 'fake news' campaign against the political press corps to Twitter several times, including some statements that suggest challenging broadcast licenses and prompting congressional investigations into media bias

Press shield laws preserve the right of journalists to refuse to disclose – even in court – their information sources. There is no federal press shield law, but laws in at least 40 states do cover reporters in that way.

Trump's longstanding habit of sniping at journalists he loves to hate reached a fever pitch last fall when he floated a wide range of remedies for what he sees as a mass media that's stacked against him.

'Why Isn't the Senate Intel Committee looking into the Fake News Networks in OUR country to see why so much of our news is just made up-FAKE!' he tweeted on October 5.

Hours later the president directly challenged the legitimacy of major broadcasters.

'With all of the Fake News coming out of NBC and the Networks, at what point is it appropriate to challenge their License?' he asked.

Trump was still at is six days later, tweeting that '[n]etwork news has become so partisan, distorted and fake that licenses must be challenged and, if appropriate, revoked.'