U.S. President Donald Trump on Wednesday threatened to regulate or shut down social media companies.

His latest threat is coming just one day after Twitter Inc. for the first time added a warning to some of his tweets prompting readers to fact check the president’s claims.

Trump, without offering any evidence, reiterated his accusations of political bias by such technology platforms in a pair of early morning posts on Twitter, saying:

“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.”

He added: “Clean up your act, NOW!!!!”