A court has accepted an indictment accusing him of "praising crime and criminals" for statements defending individuals targeted by the Turkish government's crackdown on dissent.
The indictment, filed by members of the far-right Nationalist Movement Party (MHP), stems from Kilicdaroglu's public statements over several years.
He is accused of supporting jailed Kurdish leader Selahattin Demirtas and journalists detained under counterterrorism laws.
The indictment includes Kilicdaroglu's criticism of Demirtas' imprisonment for using the term "Kurdistan," his defense of a CHP lawmaker who criticized Turkey's use of drones, and his comments referring to Kurdish fighters as "friends" or those defending their homeland.
The current CHP leader, Ozgur Ozel, has denounced the indictment as a politically motivated attempt by the MHP to silence opposition voices. He vows to resist any effort to imprison Kilicdaroglu.