The Trump administration will require prescription drug companies to post prices in TV commercials, a move that is expected to trigger lawsuits over free speech.

Health and Human Services Secretary Alex Azar called the rule, released Wednesday, the “single most significant step" any administration had taken in letting the public know how much medical goods and services cost. The administration hopes that having companies list prices will cause them to go down.

Drug companies will be forced to follow the rule in about two months, and it will apply to drugs that cost more than $35 a month and that are covered by the government health programs Medicare and Medicaid. Drug companies already have to post the major side effects of drugs in commercials, and Azar said he thought disclosing prices was just as important to help patients take control of their healthcare.

The pharmaceutical industry has pushed back on the idea of posting their prices, saying that list prices are different than what most consumers pay because health insurers, hospitals, or the government negotiate what actual spending will be.

Stephen Ubl, president and CEO of the Pharmaceutical Research and Manufacturers of America, the lead trade group for the industry, said in a statement that the group was concerned the rule would be "confusing to patients and may discourage them from seeking needed medical care. "

“While we are still reviewing the administration’s rule, we believe there are operational challenges, particularly the 60-day implementation time frame, and think the final rule raises First Amendment and statutory concerns,” Ubl said.

PhRMA's members have been instead including websites in commercials that tell patients where they can get more information about their drugs. The group on Wednesday announced it had created a new website people could use called the Medicine Assistance Tool, where customers can answer a series of questions and see whether they qualify for coupons or assistance programs that make their drugs less expensive.

Not all drug companies will fight the rule. Johnson & Johnson, for instance, began listing the prices of its blood thinner Xarelto ahead of the Trump administration's announcement.

The idea of having drug companies post prices appears to be popular with the public. A poll published last summer by the Kaiser Family Foundation found that 76% of respondents liked the idea.

[Opinion: Drug prices in ads actually hurt consumers]

Under the rule, prescription drug companies will have to tell patients how much a 30-day supply of a drug will cost them, and they can tell viewers that they may pay less if they have health insurance. Azar said that only listing a website on a commercial, as the industry has been doing, was "not acceptable." The law won't be enforced by the Food and Drug Administration, which regulates drugs, but by competitors who can sue for deceptive trade practices.

The Trump administration is looking at different corners of the drug-pricing industry to address the president's priority of lowering drug prices for patients. Azar said in a phone call with reporters Wednesday that the list price was an important part of addressing the issue because patients end up paying a significant amount out of pocket for medicines.

He noted that people who are uninsured tend to be asked to pay the full list price for drugs, and consumers often don't see savings after the healthcare industry negotiates rebates for itself.

Prescription drug companies spend more than $4 billion on TV advertising every year, prompting consumers to ask their doctors about the medicines advertised. Azar said he believed patients have the right to be armed with information about how much they might pay at the pharmacy before they sit down with their doctors to discuss whether the drugs are right for them.

"If you're ashamed of your drug prices, change your drug prices," he said. "It's that simple."