(Reuters) – A group of conservative U.S. doctors has sued the Food and Drug Administration for limiting use of the malaria drug hydroxychloroquine for COVID-19, arguing that the therapy should be made widely available to fight the pandemic.

The lawsuit represents the latest front in a highly politicized U.S. debate over access to hydroxychloroquine. The drug has been championed by President Donald Trump as a potential “game-changer” against the coronavirus, but its value has yet to be established. A clinical trial released on Wednesday found it to be ineffective in preventing infection.

The FDA, which regulates medicines in the United States, has restricted use of the drug from the national stockpile to COVID-19 patients who are hospitalized and cannot enroll in a clinical trial. States can set their own rules for prescription, with many influenced by the FDA’s warning that the drug has a risk of a side-effect of dangerous heart arrhythmias.

That harms the rights of its member doctors to prescribe as they see fit, causing “economic injury,” the Association of American Physicians and Surgeons (AAPS) argues in its suit, filed in a Michigan federal district court on Tuesday.

An FDA agency spokesperson said it does not comment on pending or ongoing litigation.

In a statement published online last week, FDA Commissioner Stephen Hahn said the agency does not prohibit physicians from prescribing medications. “It is important that patients and health care providers understand the known side effects of these drugs, including serious and potentially life-threatening heart rhythm problems,” he said.

The AAPS, a non-profit organization based in Tucson, Arizona, has a “few thousand” members, according to executive director Jane Orient. It opposes mandatory vaccination, previously waged a campaign against healthcare reforms introduced by former President Barack Obama, and has been pushing back against state restrictions on use of hydroxychloroquine as a preventive therapy for the coronavirus.

AAPS has accused state and federal agencies of “hoarding” hydroxychloroquine while patients die in an outbreak that has killed over 107,000 and infected 1.86 million in the United States to date.

The group is running a series of online seminars for doctors on the coronavirus. General counsel Andrew Schlafly discussed legal issues related to prescribing hydroxychloroquine on one in April.

“They could pump out 100 million doses of these things within a week. Everybody in our country could be given them, and that would stop this crisis overnight, most likely,” said Schlafly, who is not a doctor.

Richard Chaisson, a Johns Hopkins researcher, is running a trial of the drug to determine whether it is effective in treating patients with moderate to severe versions of the disease.

“Right now, the data for hydroxychloroquine is not compelling for any group,” he said in an interview. “Until it’s been studied, I really think it’s irresponsible to recommend it routinely outside of a clinical trial.”

Schlafly said in response: “I disagree completely… the data is that the medication is very safe.”

More than 35 states have restricted prescriptions for hydroxychloroquine, and at least five of those have rules specifically prohibiting prescribing the drug as a preventive measure.