HELENA, Mont. (AP) — One of Montana's foremost medical marijuana advocates and a longtime lobbyist will plead guilty to a federal drug charge.

Court documents filed Wednesday say Tom Daubert agreed to plead guilty to conspiracy to maintain drug involved premises.

Daubert is the founder of the advocacy group Patients and Families United. He helped draft the voter-approved initiative to legalize medical marijuana, and he has been a political and communications strategist for more than 30 years.

Daubert was a co-owner of Montana Cannabis, one of dozens of medical marijuana businesses raided last year in a federal crackdown. His attorney, Peter Lacny, says a plea agreement was in Daubert's best interest to minimize any effect on his future.

The charge carries a maximum 20-year sentence and Daubert will be required to pay $50,000.