WASHINGTON — President Donald Trump is preparing to sign an executive order Thursday aimed at curbing liability protections for social media companies, two days after he lashed out at Twitter for applying fact checks to two of his tweets.

Trump had threatened social media companies with new regulation or even shuttering on Wednesday, lashing out at the new policy he believed interfered with his political messaging, but he alone can’t do that.

The proposed order would direct executive branch agencies including the Federal Communications Commission and the Federal Trade Commission to study whether they can place new rules on the companies — though experts expressed doubts much could be done without an act of Congress.

A similar executive order was previously considered by the administration but shelved over concerns it couldn’t pass legal muster and that it violated conservative principles on deregulation and free speech.

Two administration officials outlined the draft order on the condition of anonymity because it was still being finalized Thursday morning. But a draft was circulating on Twitter — where else?

“This will be a Big Day for Social Media and FAIRNESS!” Trump tweeted Thursday morning.

Trump on Wednesday claimed tech giants “silence conservative voices.” “We will strongly regulate, or close them down, before we can ever allow this to happen.”

Press secretary Kayleigh McEnany said Trump would sign an executive order relating to social media companies but provided no further details. White House strategic communications director Alyssa Farah said Trump would sign it Thursday.

Trump and his campaign lashed out at the company after Twitter added a warning phrase to two Trump tweets that called mail-in ballots “fraudulent” and predicted “mail boxes will be robbed.” Under the tweets, there’s now a link reading “Get the facts about mail-in ballots” that guides users to a page with fact checks and news stories about Trump’s unsubstantiated claims.

Trump accused Twitter of “interfering in the 2020 Presidential Election” and insisting “as president, I will not allow this to happen.” His campaign manager, Brad Parscale, said Twitter’s “clear political bias” had led the campaign to pull “all our advertising from Twitter months ago.” Twitter has banned political advertising since last November.

Order Expected to Hold Back Federal Advertising Dollars from Social Platforms

Late Wednesday, Twitter CEO Jack Dorsey tweeted, “We’ll continue to point out incorrect or disputed information about elections globally.”

Dorsey added: “This does not make us an ‘arbiter of truth.’ Our intention is to connect the dots of conflicting statements and show the information in dispute so people can judge for themselves.”

Twitter’s decision to mark Trump’s tweets regarding mail-in balloting came as the president was sparking another social media firestorm, continuing to stoke a debunked conspiracy theory accusing MSNBC host Joe Scarborough of killing a former congressional office staffer. Prominent Republicans, including Rep. Liz Cheney and Sen. Mitt Romney, urged Trump to drop the attack, which hasn’t been marked with a fact check by the social media company.

Trump and his allies have long accused the tech giants in liberal-leaning Silicon Valley of targeting conservatives on social media by fact-checking them or removing their posts. Last year the White House unveiled a “Tech Bias Reporting tool” meant primarily to highlight cases in which conservatives believed they were being silenced.

The president’s critics, meanwhile, have scolded the platforms for allowing him to put forth false or misleading information that could confuse voters.

Some Trump allies have questioned whether platforms like Twitter and Facebook should continue to enjoy liability protections as “platforms” under federal law or be treated more like publishers, which can face lawsuits over content.

The protections have been credited with allowing the unfettered growth of the internet for more than two decades, but now some Trump allies are advocating social media companies face more scrutiny.

The draft executive order was expected to argue that actions like Twitter’s fact check labeling meant they should lose the protections of being a “platform.” Even if upheld by regulators and federal courts, it was not clear how that could affect the company’s effort to fact check Trump’s tweets.

The order was also expected to try to hold back federal advertising dollars from Twitter and other social media companies that “violate free speech principles.”

Twitter Has Said It Will Decide Internally When to Use a Label

Twitter’s first use of a label on Trump’s tweets comes as platforms gear up to combat misinformation around the U.S. presidential election. Twitter and Facebook have begun rolling out dozens of new rules to avoid a repeat of the false postings about the candidates and the voting process that marred the 2016 election.

The coronavirus pandemic has further escalated the platforms’ response, leading them to take actions against politicians — a move they’ve long resisted — who make misleading claims about the virus.

Last month, Twitter began a “Get the Facts” label to direct social media users to news articles from trusted outlets next to tweets containing misleading or disputed information about the virus. Company leaders said the new labels could be applied to anyone on Twitter and they were considering using them on other topics.

Twitter has said it will decide internally when to use a label, and on which tweets, and will draw from information curated from news outlets.

Facebook CEO Mark Zuckerberg told Fox News on Wednesday his platform has “a different policy, I think, than Twitter on this.”

“I just believe strongly that Facebook shouldn’t be the arbiter of truth of everything that people say online,” he said.

Meanwhile, Republicans were turning their fire on one of the Twitter executives responsible for adding the fact checks: Yoel Roth, head of site integrity. They’re pointing to tweets he sent in 2016 and 2017 railing against the president and his allies.

“From their bogus ‘fact check’ of @realDonaldTrump to their ‘head of site integrity’ displaying his clear hatred towards Republicans, Twitter’s blatant bias has gone too far,” tweeted Republican National Chairman Chair Ronna McDaniel.

Jack Balkin, a Yale University law professor and First Amendment expert, said any attempt to regulate social media companies for the content on their sites would likely need congressional input and approval — and probably face strong legal challenges.