The American Medical Association, the largest advocacy group for doctors in the United States, on Monday announced its opposition to the Senate’s bill to replace Obamacare.

“Medicine has long operated under the precept of Primum non nocere, or ‘first, do no harm.’ The draft legislation violates that standard on many levels,” James Madara, AMA’s CEO, wrote in a letter to Senate leaders.

Madara wrote that provisions in the Senate’s draft legislation, like less generous subsidies and broader waivers for states, “will expose low and middle income patients to higher costs and greater difficulty in affording care.” The group is also concerned about the deep cuts to Medicaid that the Senate’s draft bill imposes.

“We sincerely hope that the Senate will take this opportunity to change the course of the current debate and work to fix problems with the current system. We believe that Congress should be working to increase the number of Americans with access to quality, affordable health insurance instead of pursuing policies that have the opposite effect, and we renew our commitment to work with you in that endeavor,” Madara concluded in the letter.

Read the letter: