The Los Angeles Times and Washington Post announced they had ended their decades-long practice of officially backing a presidential contender.

That drew a pointed retort from the Post's former top editor Marty Baron, who suggested his old newspaper was giving in to intimidation from Republican Donald Trump.

"This is cowardice," Baron said on X, "with democracy as its casualty."

The generally left-leaning newspaper -- owned by the billionaire Jeff Bezos, the founder and owner of Amazon -- was about to back Kamala Harris but said Friday that it would no longer endorse presidential candidates in any future election.

That decision, following a similar move by the Los Angeles Times, sent shock waves through politics and journalism.

The Post, in seeking to justify its choice, said: "Our job as the newspaper of the capital city of the most important country in the world is to be independent. And that is what we are and will be."

But the newspaper's guild, representing its journalists, said it was "deeply concerned," adding that "an endorsement for Kamala Harris was already drafted, and the decision to not publish was made by The Post's owner, Jeff Bezos."

A source close to the paper's leadership denied that to AFP.

Earlier in the week, the billionaire owner of the Los Angeles Times, Patrick Soon-Shiong, overruled the paper's editorial staff, which also wanted to endorse Vice President Harris.

Several Times employees of both papers resigned in protest, including editorials editor Mariel Garza.

"I want to make it clear that I am not okay with us being silent," she said in an interview.

"In dangerous times, honest people need to stand up."

Billionaires' power 

The Trump campaign responded with delight, saying, "Kamala is such an empty vessel, the Washington Post has decided to nuke presidential endorsements altogether rather than back her candidacy.

Many readers of both papers expressed outrage, vowing to cancel their subscriptions.

The decision not to endorse stemmed partly from the papers "not wanting to alienate potential readers," said Dannagal Young, a professor of communications at the University of Delaware.

But "let's be clear," she added. "The media mogul class is probably not very inclined to want to alienate (a person) who could be the president. 

"People want to be on the good side of Donald Trump."

Many media owners have financial interests linked to the government. Bezos holds shares in companies with substantial contracts with the administration, including the Pentagon.

Dan Kennedy, a journalism professor at Northeastern University, said media owners were engaging in "anticipatory obedience."

For them "to take a pass on the presidential race this late in the campaign smacks of giving in to the punishment they might be subjected to if Trump returns to office," he added in a blog.

Fading print giants 

Nonetheless, Harris this year won endorsements from the New York Times, the Boston Globe, Rolling Stone magazine and the Philadelphia Inquirer.

Trump, for his part, won the backing of the conservative Washington Times and the New York Post, a tabloid owned by magnate Rupert Murdoch.

But while the campaigns have increasingly bet on the influence of newer platforms like podcasts and TikTok, endorsements from prestige media "still matter," said Jane Hall, a communications professor at American University.

The reluctance to endorse comes at "a moment when Donald Trump is talking about going after the licenses of television stations, punishing journalists further and attacking the free press in an administration that hasn't even started."

In recent days, Trump has again blasted the news media as "the enemy of the people."

Hall said the Washington Post -- which in 2017 added the phrase "Democracy Dies in Darkness" to its masthead -- was "courageous in covering the January 6 insurrection and in standing up to threats against the media." 

So its decision now to withhold an endorsement "will send a chilling effect to journalists," she said. "It's very shocking."