Marijuana is currently designated as a Schedule I substance under the Controlled Substance Act. Schedule I is the most restricted category, reserved for drugs like heroin with no accepted medical purpose and high potential for abuse. The DEA is considering reclassifying weed as Schedule III, where it would join drugs with moderate risk of physical or psychological dependence, like testosterone and Tylenol with codeine.

The move wouldn’t federally legalize marijuana, but it would signal a new governmental approach to weed. Rescheduling would make it easier to research marijuana’s health effects and could change some aspects of cannabis commerce.

Lankford and Rep. Pete Sessions of Texas penned a letter to U.S. Attorney General Merrick Garland this week asking him to withdraw the Department of Justice’s proposed reclassification. Lankford writes the Biden administration’s push to reschedule weed is “responding to the popularity of marijuana and not the actual science.”

“The fact that states have labeled marijuana as “medicine” does not change the nature of the drug,” the letter reads. “The FDA has never approved the marijuana that is being sold in dispensaries across the country as ‘medicine’ for any disease or condition.”

The letter also points out that although the proposed rules change comes jointly from the DEA and the DOJ, DEA Administrator Anne Milgram didn’t sign it, and her agency declined to reschedule weed twice in 2016. Lankford’s letter argues the DOJ may be trying to circumvent the DEA with this proposed rules change.

Twenty-four other Republican lawmakers from both chambers signed onto the letter, including Oklahoma Congressman Josh Brecheen. Garland has not yet publicly responded to the letter.