US President Donald Trump will sign an executive order on social media companies on Thursday, White House officials said after Mr Trump threatened to shut down the platform he accused of stifling conservative voices.
The officials, who spoke to reporters travelling with Mr Trump to Washington from Florida aboard Air Force One on Wednesday, gave no further details.
Before leaving for Florida earlier in the day to observe a space launch that was postponed because of bad weather, Mr Trump again accused Twitter Inc and other social media of bias without offering evidence.
It was unclear how Mr Trump could follow through on the threat of shutting down social media companies.
The American Civil Liberties Union said the First Amendment of the US Constitution limits any action Mr Trump could take to regulate such platforms.
Twitter has now shown that everything we have been saying about them (and their other compatriots) is correct. Big action to follow!— Donald J. Trump (@realDonaldTrump) May 27, 2020
Facebook Inc's Chief Executive Officer Mark Zuckerberg, commenting on Mr Trump's threats against social media companies, said censoring a platform would not be the "right reflex" for a government worried about censorship.
"I'll have to understand what they actually would intend to do, but in general I think a government choosing to censor a platform because they're worried about censorship doesn't exactly strike me as the right reflex there," Mr Zuckerberg said in an interview with Fox News Channel.
.@Twitter is now interfering in the 2020 Presidential Election. They are saying my statement on Mail-In Ballots, which will lead to massive corruption and fraud, is incorrect, based on fact-checking by Fake News CNN and the Amazon Washington Post....— Donald J. Trump (@realDonaldTrump) May 26, 2020
Fox played only a brief clip of the interview and said it would be aired in full on Thursday.
Twitter declined comment on news of Mr Trump's plans and Google did not immediately comment.
Separately, a three-judge panel of the US Court of Appeals in Washington on Wednesday upheld the dismissal of a suit brought by a conservative group and right-wing YouTube personality against Google, Facebook, Twitter and Apple alleging they conspired to suppress conservative political views.
Republicans feel that Social Media Platforms totally silence conservatives voices. We will strongly regulate, or close them down, before we can ever allow this to happen. We saw what they attempted to do, and failed, in 2016. We can’t let a more sophisticated version of that....— Donald J. Trump (@realDonaldTrump) May 27, 2020
Mr Trump's latest dispute with social media emerged after Twitter on Tuesday for the first time attached a warning to some of his tweets prompting readers to fact check the president's claims.
In the tweets tagged by Twitter, Mr Trump made unsubstantiated claims about mail-in voting. Mr Trump falsely claims that mail-in ballots lead to vote fraud and ineligible voters getting ballots.
"Republicans feel that Social Media Platforms totally silence conservatives voices. We will strongly regulate, or close them down, before we can ever allow this to happen," Mr Trump said in a pair of additional posts on Twitter on Wednesday.
The president, a heavy user of Twitter with more than 80 million followers, added: "Clean up your act, NOW!!!!"