Democratic voters will decide Tuesday whether District Attorney Larry Krasner deserves a third term or whether his primary challenger, former Municipal Court Judge Patrick Dugan, should be Philadelphia’s next top prosecutor.

The district attorney race is the most high-profile contest on the primary ballot in Philadelphia on Tuesday, and it will likely be decisive because no Republican has filed to run.

A former criminal defense attorney, Krasner notched a surprise victory in 2017 that made him a national figure in the progressive prosecutor movement. The challenge from Dugan, an Army veteran seen as a tough-on-crime alternative to Krasner, represents the latest test of whether Philadelphians support the incumbent‘s vision for criminal justice reform.

Here’s what you need to know about the Democratic primary for district attorney.

Krasner has won endorsements from progressive groups including the Working Families Party, OnePA, and PhillyNOW, the local chapter of the National Organization for Women. He is also backed by the unions for Philadelphia public school teachers and non-uniformed city workers.

“Larry Krasner has a proven track record of standing up to bullies from Donald Trump to the gun lobby to shooting groups, and has made our city safer with law enforcement partners,” Krasner spokesperson Anthony Campisi said. “We‘re running to continue delivering on those promises.”