Sen. Bernie Sanders, I-Vermont, is stepping up his attack on Novo Nordisk over the prices the company charges in the U.S. for its wildly popular diabetes and weight loss drugs.

Sanders, the chairman of the Senate Committee on Health, Education, Labor and Pensions (HELP), is asking the committee to vote on whether it should subpoena Novo’s North American operations chief Doug Langa to face questions at a hearing on July 10 about the company’s pricing tactics. The vote is scheduled for Tuesday, June 18.

Sanders’ initiative comes seven weeks after the HELP Committee launched an investigation into Novo’s prices. Last month, the committee issued a dire warning that the drugs—and others in their class—have the “potential to bankrupt Medicare, Medicaid and our entire health care system.”

In his announcement on Tuesday, Sanders pointed out that the committee's investigation determined Novo charges $969 per month for Type 2 diabetes medicine Ozempic in the U.S. versus $155 monthly in Canada, $122 in Denmark and $59 in Germany.

Similarly, for obesity drug Wegovy, Novo charges $1,349 per month in the U.S. compared to $92 monthly in the U.K., Sanders added.

The committee has reached out “time and time again” to Novo seeking its voluntary attendance at the hearing next month, Sanders said Tuesday. The company has “repeatedly” denied those committee efforts, Sanders said.

Novo has a different characterization of its discussions with the committee.

"Every time the Chairman has made a request to Novo Nordisk we have responded and cooperated," a company spokesperson wrote. "On multiple occasions, we have communicated our CEO’s willingness to testify and offered several dates for a hearing. Based on our continued cooperation, we feel that issuing a subpoena is unnecessary.

"We are committed to a hearing that aligns with the Chairman’s established committee practices and to developing meaningful solutions to enhance patient access and affordability."

The U.S. Chamber of Commerce and industry association PhRMA blasted Sanders' pursuit of a subpoena.

“Senator Sanders continues to use his position to exploit the popularity of revolutionary new medicines and attack one company, who is cooperating and already agreed to testify, to further his own political agenda," Alex Schriver, PhRMA's senior vice president of public affairs, said in a statement. "This isn’t a good-faithed effort to address the challenges patients are facing; it’s a political crusade."

In February of this year, CEOs from Bristol Myers Squibb, Johnson & Johnson and Merck—under the threat of a subpoena from the HELP Committee—appeared at a hearing answering questions about why they charge more in the U.S. for their drugs than in other countries.

The Chamber of Commerce wrote that Sanders is "abusing the power of his committee to intimidate companies."

"In a country founded on the principles of the rule of law and respect for free enterprise, the spectacle of an elected official targeting reputable companies for what appears to be political gain undermines the very foundations of the American economic system."

Editor's note: This story was updated with comments from Novo Nordisk, PhRMA and the U.S. Chamber of Commerce.