President Donald Trump complained again about supposed bias against conservatives at social media companies and said the U.S. government should sue Google and Facebook Inc. for unspecified wrongdoing.

Trump complained in an interview with Fox Business Network on Wednesday that social media companies are run by Democrats and that Twitter has somehow made it difficult for people to follow his @realDonaldTrump account, from which he tweets prolifically.

He said that the U.S. “should be suing” Facebook and Google, adding “and perhaps we will,” without saying what the companies would be sued for.

Social media companies have sought to more aggressively police their sites for what they consider hate speech and fraudulent accounts, but say they have no policies targeting conservatives.

Trump’s threat comes after Project Veritas, a conservative organization known for deceptively edited hidden-camera videos, released footage this week allegedly depicting a Google employee saying the company wants to prevent Trump’s re-election.

Google (GOOG), Facebook (FB) and Twitter shares (TWTR) dipped on the news and recovered in pre-market trading.

Representatives for Alphabet Inc.‘s Google and Facebook didn’t immediately respond to requests for comment.

Trump’s Justice Department and the Federal Trade Commission have taken the first steps toward investigating four big technology companies for antitrust violations by splitting jurisdiction over them. The Justice Department has taken responsibility for Google and Apple Inc., while the FTC will oversee Facebook Inc. and Amazon.com Inc.

Separately, state attorneys general, including Nebraska’s Doug Peterson and Louisiana’s Jeff Landry -- both Republicans -- are advancing a broad inquiry into whether the biggest U.S. technology platforms are violating antitrust and consumer protection statutes.