The right-leaning tabloid The Daily Mail was first to report that the prime minister said last October that he would rather see "bodies pile high in their thousands" than put the country into another lockdown.
Johnson flatly denied the story on Monday, with news agencies quoting him dismissing it as "total rubbish." But several more outlets — including The Guardian newspaper, which leans to the left, and broadcaster ITV — have confirmed versions of the story, citing anonymous sources. Even the typically cautious BBC has attributed the phrase to Johnson, quoting sources familiar with the comments. CNN has not verified the reported remark.
The sheer volume of reports from such a broad swathe of the news media is noteworthy, putting the press on a collision course with a prime minister who has frequently sparred with reporters and previously refused to participate in a major televised election debate.
"It was pretty remarkable to see both the BBC and ITV go out on such a limb about this, they've never done that before," said Suzanne Franks, a journalism professor at City University of London.
For the BBC in particular to have taken such a step, which has the potential to be "damaging and controversial," indicates the high degree of confidence they have in their sources, Franks added. "The BBC are so terrified at the moment about upsetting the government."
The public service broadcaster's primary source of revenue — fees collected from viewers — is under constant threat of being cut or scrapped by the government.
"It's clear that the BBC TV licence fee has a limited shelf life in a digital media landscape," Julian Knight, the chair of a parliamentary committee reviewing public service broadcasting, said in a report published last month.
Johnson is known for making controversial and even offensive remarks, but there may be a political price to pay for comments about a virus that has killed more than 127,000 people in the United Kingdom.
'Boris On The Ropes,' was The Daily Mail's front page headline on Tuesday. The unusually critical lead story in a newspaper ordinarily supportive of the
Conservative government was likened to Fox News challenging the Republican Party in the United States.
"Has Fox News ever taken on the top Republican the way the Daily Mail is, for example, taking on Boris Johnson today?" Rasmus Nielsen, director of the Reuters Institute for the Study of Journalism, asked on Twitter.
Charlie Beckett, the director of Polis, a media think tank at the London School of Economics, said the episode would test Johnson's ability to brush off damaging stories and accusations that he's been untruthful.
Peter Oborne, a former chief political commentator of The Daily Telegraph and a former colleague of Johnson's at The Spectator, chronicled his history of bogus claims and falsehoods in a book called "The Assault on Truth: Boris Johnson, Donald Trump and the Emergence of a New Moral Barbarism" published earlier this year.
"[Johnson] operates on a kind of Trumpian basis," Beckett, a former BBC journalist, told CNN Business. "It doesn't matter quite exactly what I say because I'm known as somebody full of rhetoric and you never quite know whether I'm joking or serious," he added.
"With this one it's really hard for him to [use that defense]. In that sense the journalists are excited about the idea of trying to pin down a repeat offender."
The comment about bodies piling high is a "cut through" issue that "everybody can have a view on," said Franks.
But if the Conservative Party wins contested seats in local elections next week, it could show that the media is out of touch with what ordinary people care about, she added.