President Donald Trump escalated his feud against social media companies, signing an executive order Thursday challenging the liability protections that have served as a bedrock for unfettered speech on the internet.

Still, the move appears to be more about politics than substance, as the president aims to rally supporters after he lashed out at Twitter for applying fact checks to two of his tweets.

Trump said the fact checks were “editorial decisions” by Twitter and amounted to political activism. He said it should cost those companies their protection from lawsuits for what is posted on their platforms.

Trump and his allies, who rely heavily on Twitter to verbally flog their foes, 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.

“We’re fed up with it,” Trump said, claiming the order would uphold freedom of speech.

It directs executive branch agencies to ask independent rule-making agencies including the Federal Communications Commission and the Federal Trade Commission to study whether they can place new regulations on the companies — though experts express doubts much can be done without an act of Congress.

Trump, who has likely used Twitter to spread his messages and platforms more than any other U.S. president, signed the order Thursday afternoon in Washington.

The president himself used — what else? — Twitter to promote his plans Thursday morning.

Trump's ire against Twitter came after the global social media giant added a warning phrase to two Trump tweets that called mail-in ballots "fraudulent" and predicted that "mail boxes will be robbed," among other things.

Under the tweets, there is now a link reading "Get the facts about mail-in ballots" that guides users to a Twitter "moments" page with fact checks and news stories about Trump's unsubstantiated claims.

Trump’s executive order will almost certainly be challenged in court. The president can’t unilaterally regulate or close the companies, and any effort would likely require action by Congress.

Trump’s administration has shelved a proposed executive order empowering the Federal Communications Commission to regulate technology companies, citing concerns it wouldn’t pass legal muster. But that didn’t stop Trump from issuing strong warnings.

There has been no immediate reaction from Twitter to the president’s threats.

Twitter’s decision to mark the president’s tweets regarding mail-in balloting came as the president was sparking another social media firestorm regarding a conspiracy theory accusing MSNBC host Joe Scarborough of killing a former staffer.

The husband of a woman who died by accident two decades ago in an office of then-U.S. Rep. Scarborough is demanding that Twitter remove the president’s tweets suggesting Scarborough, now a fierce Trump critic, killed her.

Prominent Republicans, including Rep. Liz Cheney and Sen. Mitt Romney, urged Trump to drop the attack — which has not been marked with a fact check by the social media company.

Trump replied on Twitter, accusing the platform of “interfering in the 2020 Presidential Election” and insisting that “as president, I will not allow this to happen.” His 2020 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 all political advertising since November.

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 that social media companies face more scrutiny.

“Big tech gets a huge handout from the federal government,” Republican Sen. Josh Hawley told Fox News. “They get this special immunity, this special immunity from suits and from liability that’s worth billions of dollars to them every year. Why are they getting subsidized by federal taxpayers to censor conservatives, to censor people critical of China?”

It's Trump vs. Biden this November

Twitter’s first use of a label on Trump’s tweets comes as platforms gear up to combat misinformation about 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.

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 then the new labels could be applied to anyone on Twitter, and that it was considering using them on other topics.

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

Facebook CEO Mark Zuckerberg weighed in on the matter during a Fox News interview Wednesday. “We have a different policy, I think, than Twitter on this,” he said. “I just believe strongly that Facebook shouldn’t be the arbiter of truth of everything that people say online.”

The Associated Press contributed to this report.