A former state representative, a Clean Elections worker and a civil rights advocate are competing for a vacant seat representing part of Portland in the Maine Legislature. Herbert Adams, Anna Kellar and Rachel Talbot Ross are running in the June 14 Democratic primary for House District 40, which encompasses the western half of the city’s peninsula and part of the Oakdale neighborhood. The winner will face Republican Carol Taylor and Green Independent Russell Hoskins in the November election. The seat is currently held by Ben Chipman, who is running for the state Senate. Adams held the seat from 2002 until 2010, when he had to step down because of term limits.