Lately social media communities have been disappointed and upset about what many believe is a massive amount of select censorship, manipulation of analytics/engagement/data, and coercive manipulation of expression.

United States President, Donald Trump threatened to regulate social media companies after Twitter TWTR labeled two of his tweets about mail-in voting with a “fact check,” which said the president falsely claimed mail-in ballots would lead to a rigged election and widespread fraud.

There is NO WAY (ZERO!) that Mail-In Ballots will be anything less than substantially fraudulent. Mail boxes will be robbed, ballots will be forged & even illegally printed out & fraudulently signed. The Governor of California is sending Ballots to millions of people, anyone…..

— Donald J. Trump (@realDonaldTrump) May 26, 2020

Several state governments, including some led by Republicans, have encouraged citizens to vote by mail given concerns about the spread of the coronavirus pandemic. Experts have found that instances of widespread ballot fraud are rare. On Tuesday evening, President Trump accused Twitter of “interfering in the 2020 Presidential Election” by issuing a fact check.

“Twitter is completely stifling FREE SPEECH, and I, as President, will not allow it to happen!” Mr. Trump wrote on Twitter.

….Twitter is completely stifling FREE SPEECH, and I, as President, will not allow it to happen!

— Donald J. Trump (@realDonaldTrump) May 26, 2020

Twitter’s decision to fact-check President Trump’s mail-in voting tweets comes as the president continues to propagate a conspiracy theory about MSNBC host Joe Scarborough, insinuating that he was somehow responsible for the death of a woman who worked in his office when he was a congressman. The woman’s husband, Timothy Klausutis, has asked Twitter to take down Mr. Trump’s tweets about his wife’s death, calling them “horrifying lies.”

Twitter said it will not remove the tweets.

“We are deeply sorry about the pain these statements, and the attention they are drawing, are causing the family,” a spokesperson said in a statement to CBS News on Tuesday. “We’ve been working to expand existing product features and policies so we can more effectively address things like this going forward, and we hope to have those changes in place shortly.”

In an interview with Fox News anchor Dana Perino, Facebook CEO Mark Zuckerberg rebuked Twitter for its decision to tag two of President Donald Trump’s tweets about mail-in voting with fact-check links, saying that:

“I just believe strongly that Facebook shouldn’t be the arbiter of truth of everything that people say online,” he said. “Private companies probably shouldn’t be, especially these platform companies, shouldn’t be in the position of doing that.”

Republicans have long claimed that Facebook, based in the liberal stronghold of Silicon Valley, is biased against conservatives, and Twitter’s fact check only intensified that criticism, with Trump tweeting that Twitter was “interfering” in the 2020 election and stifling free speech. Rep. Matt Gaetz (R-FL) said he is drafting a bill to walk back Section 230 of the Communications Decency Act, a vital legal shield that prevents tech platforms from being liable for what users post.

Since the 2016 election, Zuckerberg has repeatedly said that private tech companies shouldn’t decide what’s true or false. Facebook’s stance on Trump’s tweets echoes its policies surrounding political ads, which came under fire earlier this year because Facebook allows politicians to lie in them without being fact checked. Twitter, for its part, split from Facebook and banned political advertising altogether.