(JEFFERSON CITY, Mo., AP) — A group backing medical marijuana in Missouri says it doesn’t have enough valid signatures but will go to court to get a proposed constitutional amendment on November’s ballot.

New Approach Missouri campaign spokesman Jack Cardetti said Monday that the initiative is short about 2,200 signatures in a congressional district that covers the St. Louis area.

That’s because local election authorities invalidated about 10,700 signatures.

Cardetti said the campaign will go to court in an attempt to overturn some of the invalidated signatures and get the measure on the Nov. 8 ballot.

The proposal would allow the use of marijuana for medical purposes and impose a 4 percent sales tax on medical marijuana sales. The state would set up a licensing program with fees.