Minnesota Senate Republicans on Thursday will make a motion to expel their colleague Sen. Justin Eichorn following a federal criminal charge that he solicited sex from someone he thought was 17, but turned out to be an undercover officer.

A growing group of lawmakers called for Eichorn’s resignation on Wednesday and said they’ll try to vote to expel him if he doesn’t step aside voluntarily.

Fellow Republicans are calling on a Minnesota state senator to resign after police in suburban Bloomington arrested him for investigation of allegedly soliciting a minor for prostitution.