President Trump has an executive order on his desk that could trigger an antitrust investigation into Google, Facebook and other tech giants amid allegations of ­anti-conservative bias on their platforms.

If the order is signed, it would direct government agencies to use their authority “to promote competition and ensure that no online platform exercises market power in a way that harms consumers, including through the exercise of bias.”

The document, first reported by Bloomberg News on Saturday, also orders federal agencies to “thoroughly investigate whether any online platform has acted in violation of the antitrust laws.”

Web-based companies are subject to regulation by a host of agencies, but antitrust action could potentially be more damaging than other government moves.

“Because of their critical role in American society, it is essential that American citizens are protected from anti-competitive acts by dominant online platforms,” the order says. It adds that consumer harm — a key measure in antitrust investigations — could come “through the exercise of bias.”

But Samuel Weinstein, an assistant professor at Cardozo School of Law who worked in the Justice Department’s antitrust division under Presidents George W. Bush and Barack Obama, says it’s not clear that complaints of political bias qualify as antitrust violations.

For example, Twitter or Facebook may ban people from using their service because they are private companies and there is no right to use them, Weinstein said.

“Antitrust is about competition,” he explained, but that involves business, not the marketplace of ideas.

Trump tweeted on Aug. 18: “Social Media is totally discriminating against Republican/Conservative voices. Speaking loudly and clearly for the Trump Administration, we won’t let that happen.”

Social media companies say there’s no organized effort to downplay conservative viewpoints.

With Wires