The Concord Town Democratic Committee is hosting a public forum at 7 p.m. Wednesday at the Hunt Recreation Center for the party’s rivals in the primary for the District 3 seat on the Governor's Council. The Democratic candidates vying for the seat are incumbent Marilyn Petitto Devaney of Watertown, Harry S. Margolis of Brookline, and Charlie Shapiro of Newton. The candidates will introduce themselves and take questions from the audience. The eight-member Governor's Council acts on such issues as payments from the state treasury, criminal pardons and commutations, and approval of gubernatorial appointments, such as judges, notaries, and justices of the peace. There are 32 cities and towns in District 3. The primary is Sept. 6.