President Donald Trump speaks during a news conference on the coronavirus outbreak at the White House in Washington, February 29, 2020.

Twitter first labeled the video as misleading on Sunday afternoon, per its deepfake guidelines , which were unveiled last month as a way to combat false information ahead of the 2020 election. It was the first time the company used its "manipulated media" label since its March 5 implementation.

The Facebook warning says "Independent fact-checkers at Lead Stories say this post has false information. To help stop the spread of false news, a notice will be added to your post if you decide to share this."

Facebook released its own deepfake video policy in January, but did not immediately label the Trump post as misleading.

"Facebook's malfeasance when it comes to trafficking in blatantly false information is a national crisis in this respect," Biden's campaign manager, Greg Schultz, said in a statement. "Facebook won't say it, but it is apparent to all who have examined their conduct and policies: they care first and foremost about money and, to that end, are willing to serve as one of the world's most effective mediums for the spread of vile lies."

In the original video, which was from a Saturday campaign speech, Biden said: "Excuse me. We can only reelect Donald Trump if in fact we get engaged in this circular firing squad here. It's gotta be a positive campaign."

But Scavino kept the manipulated video short. "We can only reelect Donald Trump," the Democratic front-runner appeared to say.

"Fact-checkers rated this video as partly false, so we are reducing its distribution and showing warning labels with more context for people who see it, try to share it, or already have," Facebook told CNBC. "As we announced last year, the same applies if a politician shares the video, if it was otherwise fact-checked when shared by others on Facebook."

Lawmakers have increasingly called on social media platforms to respond to blatantly false information posted on their platforms, ahead of the November elections. It follows the 2016 election, after which Oxford University's Internet Institute said "aggressive" and misleading posts by Russian operatives sought to benefit Donald Trump.

"The video was not manipulated. Joe Biden really is that bad," said Tim Murtaugh, the Trump campaign's communications director, in a statement Monday.

By labeling posts as "misleading" or "partly false," social media companies have assumed some sort of responsibility to appease lawmakers.

The Biden video isn't the first post from Trump on social media that was edited and shared to be deceptive toward Democrats. In early February, Trump shared a video that was edited to show House Speaker Nancy Pelosi ripping up the text of Trump's State of the Union speech as Trump saluted a Tuskegee airman in the audience. However, in reality, Pelosi ripped the pages at the end of Trump's speech, which her office said was a response to Trump's misinformation.

The edited video was posted to both Facebook and Twitter. Both companies decided against removing the video that reached millions, frustrating Pelosi's office.

"I think they have a history here of promoting and making money off of content that is intentionally false," Pelosi's deputy chief of staff, Drew Hammill, said at the time.

Correction: The Facebook warning says "Independent fact-checkers at Lead Stories say this post has false information. To help stop the spread of false news, a notice will be added to your post if you decide to share this." An earlier version misstated the warning.

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