LITTLE ROCK, Ark. (AP) — The group behind one of two efforts to legalize medical cannabis in Arkansas won additional time to circulate petitions Thursday after falling short of the required signatures to put its proposal on the November ballot.

Secretary of State Mark Martin's office told Arkansans United for Medical Marijuana it had verified that 72,309 signatures the group submitted came from registered voters, falling short of the 84,859 needed. But since the group had gathered at least 75 percent of the valid signatures required, it has until Aug. 29 to collect more, Martin's office said.

David Couch, the sponsor of the marijuana proposal, said the group has been gathering signatures while the petitions were being reviewed and was confident it would make the ballot.

"We have more than enough signatures in hand right now to qualify for the ballot," Couch said. He said the group would continue gathering signatures over the next two weeks.

The proposed constitutional amendment would allow patients with certain medical conditions and a doctor's recommendation to buy cannabis from dispensaries. Arkansas voters narrowly rejected a medical marijuana proposal in 2012.

Martin's office earlier this month approved a competing medical marijuana proposal for the ballot, saying the group behind it had turned in more than enough signatures. That group, Arkansans for Compassionate Care, has urged Couch to drop his proposal and warned that having both on the ballot increases the odds they'll both fail. Unlike Couch's proposal, the measure already approved would allow patients to grow their own cannabis if they don't live near a dispensary.

Both measures face opposition from the conservative Family Council Action Committee, which plans to campaign against them. Jerry Cox, the committee's executive director, said the amendment would open the door to recreational marijuana in the state.

"This amendment establishes a powerful marijuana industry in Arkansas, and it puts that industry largely beyond the reach of Arkansas' lawmakers and citizens," Cox said in a statement.

Republican Gov. Asa Hutchinson, a former head of the federal Drug Enforcement Administration, also opposes the measures and has urged the state's medical community to speak out against them.

Martin's office on Wednesday gave the group behind a proposal to legalize casinos in three counties additional time to circulate petitions. His office is still reviewing petitions for a proposal to set limits on damages awarded in medical lawsuits.