Missouri Republican House candidate Thomas Ross has been arrested and accused of plotting to frame his primary opponent, Louise Secker, by planting cocaine and Adderall in her car or purse.

Prosecutors allege Ross provided the drugs to his former campaign manager and repeatedly followed up on the plan.

The FBI became involved after Joplin police alerted federal authorities, and investigators secretly recorded a conversation in which Ross allegedly approved an anonymous tip to police about drugs in Secker’s vehicle.

Ross has been charged with conspiring to distribute a controlled substance, although it remains unclear whether his former campaign manager will face charges, The Guardian has reported.

Despite the allegations, Ross narrowly defeated Secker by 33 votes in the August Republican primary, and Missouri Republican Party Chairman Peter Kinder has called on him to withdraw from the race.