A group seeking to legalize medical marijuana in Nebraska sued the state on Monday in an attempt to overturn a requirement that forces petitioners to get signatures from at least 5% of registered voters in 38 of the state’s 93 counties. The rule, stated in The Nebraska Consitution, prevents groups from only collecting signatures in larger cities, and makes it difficult for this measure to qualify for the ballot.

The federal lawsuit comes after the group Nebraskans for Medical Marijuana lost one of its biggest donors, forcing the campaign to rely primarily on volunteers as it scrambles to place the issue on the November general election ballot.

Organizers have until July 7 to gather roughly 87,000 signatures from registered voters.

Supporters of the measure argue that the rule in question gives disproportionate political power to Nebraska’s smallest counties. They argue that, for signature-gathering purposes, one voter in desolate Arthur County has about as much power as 1,216 voters in Douglas County, which encompasses Omaha.

Nebraskans for Medical Marijuana came close to placing the issue on the November 2020 ballot, announcing that it had met all of the signature requirements, but the state Supreme Court prevented it from going to voters on technical grounds.

A spokeswoman for Nebraska Secretary of State Bob Evnen said the lawsuit has been turned over to the state attorney general to defend. Evnen was named in the lawsuit because he’s the state’s top elections official.

Medical marijuana is currently legal in 37 US states.

The Associated Press contributed to this report.