Trump threatens to 'close' down social media platforms after Twitter fact checks claims on mail-in voting fraud

He claims social media is trying to "totally silence conservatives."

President Donald Trump on Wednesday threatened that Republicans will try to close down social media platforms a day after Twitter, for the first time, added a fact check to two of his tweets, ones concerning his unsubstantiated claims about widespread mail-in voting fraud.

Trump, in a tweet not specifically naming any platforms, said that "Republicans feel that Social Media Platforms totally silence conservative voices. We will strongly regulate, or close them down, before we can ever allow this to happen."

A few hours later, the president continued his tirade, singling out Twitter, saying that everything "we have being saying about them (and their other compatriots) is correct " and that there will be "Big action to follow."

Twitter responded late Wednesday night, defending its decision to label two of Trump's tweets.

"We added a label to two @realDonaldTrump Tweets about California’s vote-by-mail plans as part of our efforts to enforce our civic integrity policy," the company tweeted. "We believe those Tweets could confuse voters about what they need to do to receive a ballot and participate in the election process."

Twitter also shared a link to its "Civic integrity policy," which states that people can't use its platform for manipulating or interfering in elections.

"This includes posting or sharing content that may suppress participation or mislead people about when, where, or how to participate in a civic process," the policy says.

Trump has long accused social media platforms of being biased against conservative voices. In July 2019, during a White House "Social Media Summit," Trump attacked Facebook, Google and Twitter, claiming them of having “terrible bias” and silencing his supporters.

"A big subject today at the White House Social Media Summit will be the tremendous dishonesty, bias, discrimination and suppression practiced by certain companies," Trump tweeted prior to the event. "We will not let them get away with it much longer."

White House senior adviser Kellyanne Conway on Wednesday backed up Trump's attacks on Twitter's new fact-check notices on his tweets during an interview with Fox News, saying that they're "relying upon the same people who attack him all day long to quote fact check him."

She took aim at Twitter's head of integrity, Yoel Roth, spelling out his handle (@yoyoel) during a hit on Fox.

"Go and read what he said," she said.

His past tweets have been making the rounds on Twitter amid all this, in particular this one from November 2016: "I’m just saying, we fly over those states that voted for a racist tangerine for a reason," Roth tweeted.

On Tuesday evening, responding to Trump's complaints about Twitter's move, Missouri Republican Sen. Josh Hawley tweeted a threat similar to Trump's.

GOP lawmakers have long searched for a way to rein in social media companies. Sen. Marco Rubio weighed on Twitter's new fact-check adds to Trump's tweets, saying that "they have now decided to exercise an editorial role like a publisher then they should no longer be shielded from liability & treated as publishers under the law."

"The law still protects social media companies like @Twitter because they are considered forums not publishers," Rubio tweeted. "But if they have now decided to exercise an editorial role like a publisher then they should no longer be shielded from liability & treated as publishers under the law."

ABC News' Trish Turner and Will Steakin contributed to this report.