Democratic presidential candidates Hillary Rodham Clinton, Martin O'Malley and Bernie Sanders pose for a photo after a democratic presidential candidate forum at Winthrop University in Rock Hill, S.C., Friday, Nov. 6, 2015. (AP Photo/Chuck Burton)

ORANGEBURG, S.C. — Hillary Rodham Clinton has long declined to endorse legalized medical or recreational marijuana at the federal level, but on Saturday, she added more specifics to her proposal to increase research into medical marijuana.

Clinton said that she supports removing marijuana from a list of schedule 1 drugs, a classification that prevents federally-sponsored research into its effects. As a schedule 1 drug, marijuana is classified among the most dangerous drugs that the federal Drug Enforcement Agency regulates.

"We haven’t done research, why? Because it’s considered a schedule 1 drug," Clinton said during a town hall meeting at Claflin University in South Carolina on Saturday. "I'd like to move it from schedule 1 to schedule 2."

The addition to her position on marijuana brings her in line with two other Democratic presidential rivals, Vermont Sen. Bernie Sanders and former Maryland governor Martin O'Malley, who both oppose marijuana's designation as a schedule 1 substance. Sanders has gone farther, saying that marijuana should not be listed among DEA regulated substances at all.

In response to Clinton's announcement, Sanders said that her position does not go far enough.

Clinton's "approach ignored the major issue," Sanders said. "Secretary Clinton would classify marijuana in the same category as cocaine and continue to make marijuana a federally regulated substance."

“If we are serious about criminal justice reform and preventing many thousands of lives from being impacted because of criminal convictions for marijuana possession, we must remove marijuana from the federal Controlled Substances Act and allow states the right to go forward, if they choose, to legalize marijuana without federal legal impediments,” he aded.

[Sanders proposes nixing marijuana from federal list of dangerous drugs]

According to the Drug Enforcement Agency, schedule 1 drugs are "defined as drugs with no currently accepted medical use and a high potential for abuse. Schedule 1 drugs are the most dangerous drugs of all the drug schedules with potentially severe psychological or physical dependence."

Clinton has repeatedly said that she believes states are the "laboratories of democracy" on the marijuana issue and that she would like to see more research into the health effects of medical marijuana.

"I want to see how it works before we do a national plan for the federal government," Clinton said.

Specifically, on Saturday, she said that more information is needed to determine safe dosages, the efficacy of certain varieties of the drug, and potential complications with other drugs.

[Clinton refrains from attacks while bearing the brunt of her opponents’]

Before her announcement, Clinton's critics noted that the DEA's classification of marijuana as a schedule 1 drug makes it more difficult for research to be approved.

Clinton will also lift restrictions on obtaining marijuana for medical studies, by allowing researchers to obtain the drug through licensed suppliers in states where medical marijuana is legal.

Other marijuana advocates say moving the drug to schedule 2 is not enough. Marijuana users and businesses would still risk federal penalties for using and selling the drug.

"The rescheduling of marijuana is a step in the right direction, but only going down to Schedule II is mostly a symbolic move," said Tom Angell, chairman of the pro-marijuana group Marijuana Majority. "It may make research slightly easier, but on its own wouldn't do anything to protect seriously ill people who are using marijuana in accordance with state laws from being harassed by the DEA."

"Only changing the federal criminal statutes can effectively do that," he added.

O'Malley also supports moving marijuana to the schedule 2 list. Sanders is the only presidential candidate who has proposed removing marijuana altogether from the schedule of controlled substances regulated by the DEA.

This post has been updated.