(CNN) -- The Montana House of Representatives voted 63-37 Thursday to repeal the state's six-year-old medical marijuana law.
House Speaker Mike Milburn has argued Montana was "duped" into passing the act.
According to CNN Great Falls affiliate KRTV, Milburn said many of the people who have been approved for medical marijuana "aren't the terminally ill."
Milburn has said the medical marijuana law led to an abundance of the drug and an illegal trade, Helena affiliate KTVH said.
The measure, overwhelmingly passed as a voter initiative in 2004, allows people with debilitating or terminal illnesses to use medical marijuana to treat pain and other chronic symptoms.
Democrats who oppose the repeal measure argue that lawmakers should instead heavily regulate the industry and leave it to voters whether to repeal their own initiative, according to KTVH.
"A great majority of these people are honest people and they are using it because they're in a great deal of pain, they need medical cannabis," said Democratic Rep. Tim Furey.
The measure must pass a third reading in the House before it can be sent to the Senate.