Oklahoma, one of the most conservative states in the U.S., will ask voters next year if they want to legalize recreational marijuana.

The proposal, known as State Question 820, will be on the ballot for a special election on March 7, Gov. Kevin Stitt (R) announced Tuesday after supporters of the proposal submitted enough voter signatures. If its passed, Oklahomans ages 21 and up will be allowed to use the drug and purchase it from licensed retailers.

A 15% excise tax on those sales would fund the implementation of the law, with any excess spent on substance abuse programs in schools, addiction treatment programs and other state spending needs.

Last year, around 4,000 people in Oklahoma were arrested for selling or possessing marijuana, making up more than one-third of drug-related arrests in the state, the advocacy group NORML reports.

Medical marijuana is already legal in Oklahoma.

We are grateful the voices of over 164,000 Oklahomans who signed the petition and want to vote on legalizing recreational marijuana for adults in Oklahoma have been heard, said Yes On 820s campaign director, Michelle Tilley.

SQ 820s supporters were hopeful the proposal would be approved in time to appear on Novembers midterm election ballot. However, a new signature verification process that the Oklahoma Secretary of States office conducted with an outside firm took more than twice as long as usual, the campaign said.

Democrats were also hopeful that the proposals appearance on the ballot in November would energize liberal voters to turn up at the polls.

Stitt, a Republican, has said he opposes the legalization proposal because the federal government still considers marijuana a dangerous, illegal substance.

Do I wish that the feds would pass legalized marijuana? Yes. I think that would solve a lot of issues from all these different states, Stitt previously told The Associated Press . But in our state, just trying to protect our state right now, I dont think it would be good for Oklahoma.

Despite no documented deaths associated with marijuana overdoses, U.S. drug officials still categorize it as a Schedule I drug , ranking it with heroin and ecstasy in terms of risk levels.