Sen. Mike Lee is dangling the possibility of breaking up what he says are monopolies by social media companies like Twitter, Google and Facebook for what he says is their “heavy-handed censorship” of conservatives including President Donald Trump.

“I view your heavy-handed censorship as a sign of exactly the sort of degraded quality one expects from a monopolist,” Lee wrote in a letter this week to leaders of the companies.

“In any other business, you would never dream of treating your customers the way you treat those with views you don’t like. That is, unless you know your customers have no other serious options.”

Lee’s criticism has extra weight because he is chairman of the Senate Judiciary Antitrust Subcommittee, which oversees legislation about monopolies. He announced this week that he will hold a hearing on Sept. 15 on whether Google and other tech giants are “stacking the deck” in online advertising.

Lee asked the leaders of Google, Facebook, Twitter and Squarespace to answer numerous questions about how and why they moderate comments online — and he attacked what he says is their warping of public debate by unfairly silencing many conservatives.

“In recent years, conservative voices like The Federalist, PragerU, President Trump, Senator Marsha Blackburn, Senate Majority Leader Mitch McConnell, Donald Trump Jr., churches, religious schools, Christian groups and others have found themselves deplatformed, demonetized or otherwise penalized for expressing their opinions,” Lee wrote.

He complained that Facebook, Twitter and Google’s YouTube this week “each censored video of licensed medical professionals discussing COVID-19.”

They removed a video — which President Trump had retweeted — published by the right-wing Breitbart News that featured a group of people wearing white lab coats calling themselves “America’s Frontline Doctors” who made dubious claims, including that masks are not needed to fight COVID-19 and that studies saying hydroxychloroquine is ineffective are “fake science.”

Lee also complained that Squarespace shut down a website run by the same doctors.

“While I am not in a position to endorse or refute any of the doctors’ comments, I believe that we should err on the side of encouraging more speech, not less,” Lee wrote.

“Fortunately we are not without recourse,” Lee warned, adding that as tech companies acquire more competitors, “Congress must ensure that our antitrust laws are properly enforced.”

So he asked them several questions to “account for your conduct and to provide transparency over how you police your platforms.”

Among those questions:

• What content-moderation standards to you employ when you remove content from your platform, where the content does not violate state or federal laws?

• If Centers for Disease Control guidance is the basis for removing content regarding COVID-19, is that standard applied consistently? For example, since the CDC says that it is safe for schools to open, do you remove content from your platform that opposes reopening schools?”

• What are the prerequisites for a content-moderator position at your company? Do you inquire about the political or other beliefs of a candidate before making a hiring decision?

• How do you ensure that a content-moderation decision is not influenced by the personal beliefs or political views of the moderator?

• Do you coordinate the removal of specific content with other online platforms or competitors?

Lee’s letter also comes after Utah’s other GOP senator, Mitt Romney, on Thursday told colleagues during a Senate Foreign Relations Committee hearing that attacking such tech giants is unwise and could help China in global economic competition.

“I know there’s great interest sometimes politically to go after some of the big tech companies, Google, Amazon and Facebook, and berate them for their market power. And if they violate American antitrust laws, why, that’s totally appropriate,” Romney said.

“But I would note that we’re in a global competition. And China has been successful in driving a lot of Western companies out of business. They’ve not been successful in driving companies like these out of business.”

Romney added, “The last thing we ought to be doing is trying to knock down businesses in the United States that are succeeding on a global stage. So, we need to be careful not to flex our muscle, to berate those entities that are successful and are beating China.”