Blackman, a former business consultant, works with a local nonprofit focused on social justice and launched a startup video production business.
Incumbent McDonald, 81, has served on the PSC for about 16 years. He lives in Habersham County and is a partner in a funeral home business with his son and daughter-in-law.
Blackman lost in a run against McDonald in 2014, getting about 42% of the vote.
This year’s general election will include another PSC contest, pitting Savannah Democrat Robert Bryant, who held executive positions in higher education, against incumbent Jason Shaw, a former state legislator and an appointee of former Gov. Nathan Deal.