A Republican candidate for a Missouri State House seat has been charged with a federal offense after allegedly attempting to plant drugs on his primary opponent, federal prosecutors announced.

Thomas Christopher Ross, who won the Republican primary last month for Missouri House District 161 in Joplin, was charged Wednesday with conspiring to distribute a controlled substance. Investigators allege that Ross plotted to plant cocaine and Adderall in the car of Louise Secker, who was his opponent in the primary.

Ross's campaign manager contacted police in July, stating that Ross had given him drugs and instructed him to plant them on Secker. The campaign manager then provided authorities with a bag containing cocaine and an Adderall pill, which tests confirmed were real, according to the criminal complaint.

The campaign manager told investigators that Ross likely had a prescription for Adderall, suggesting the origin of the pill. Alleged text messages exchanged between Ross and the campaign manager, dating back to May, were also presented as evidence of the plot, the complaint stated.

The police enlisted the FBI to assist in the investigation. On July 31, the FBI provided the campaign manager with a covert recorder. During a meeting on that date, the campaign manager informed Ross that he still possessed the drugs and asked if Ross still wanted him to attempt to plant them on Secker. Ross allegedly agreed and suggested calling in an anonymous tip about drugs in Secker's car, reportedly telling the campaign manager, "If you can pull it off...pull it off."

Four days after this alleged conversation, Ross defeated Secker in the primary by a narrow margin of 33 votes. He was slated to face Democratic candidate Aaron Metzger in the general election.

Ross was held at the Joplin Municipal Jail. He has not yet entered a plea, and a preliminary and detention hearing is scheduled for September 9. His public defender had not immediately responded to requests for comment, and Ross's campaign also did not immediately return messages.

Missouri Republican Party Chairman Peter Kinder issued a statement Wednesday, calling on Ross to withdraw from the race and stating, "The people of Southwest Missouri deserve nothing less than leadership they can trust."