Pharmaceutical companies will have to reveal the price for many prescription drugs in TV commercials, under a new rule announced by the Trump administration Wednesday. The requirement is part of President Trump's efforts to crack down on drug costs — one of his few initiatives to earn wide bipartisan support.

Under the rule, which is set to go into effect over the summer, drugmakers will have to disclose prices in ads for any medication that costs more than $35 for a month's supply. It's similar to the current requirement for drug companies to spell out a drug's side effects in TV ads.

"Historic transparency for American patients is here," the president tweeted. "If drug companies are ashamed of those prices—lower them!"

Big announcement today: Drug companies have to come clean about their prices in TV ads. Historic transparency for American patients is here. If drug companies are ashamed of those prices—lower them! — Donald J. Trump (@realDonaldTrump) May 8, 2019

"Requiring the inclusion of drugs' list prices in TV ads is the single most significant step any administration has taken toward a simple commitment: American patients deserve to know the prices of the healthcare they receive," Health and Human Services Secretary Alex Azar said in a statement.

Get Breaking News Delivered to Your Inbox

Drug companies immediately pushed back on the regulation. The Pharmaceutical Research and Manufacturers of America, a leading lobbying group for the industry, said Wednesday the rule could confuse consumers — since drug prices may vary widely based on insurance — and could even violate the First Amendment rights of drugmakers.

The rule will require a disclaimer noting that costs "may be different" for consumers with insurance.

Mr. Trump has been an outspoken critic of drug companies for high prices, accusing them of "getting away with murder." Republicans and Democrats in Congress have both supported calls for cutting prescription drug costs, but they don't always agree on the solutions.

The administration last year released a blueprint to lower drug costs, though many of its proposals have not been put into action. Azar in February unveiled a plan to take hidden discounts that are given drugmakers and insurers, and redirect them to consumers.