These are the potential Democratic candidates according to www.politics1.com
Renny Cushing (D) - State Rep. & Progressive Activist
Mark MacKenzie (D) - State Rep., Ex-State AFL-CIO President & Retired Firefighter
Steve Marchand (D) - Ex-Portsmouth Mayor, Consultant, '16 Candidate & '08 US Sen. Candidate
Mindi Messmer (D) - State Rep. & Environmental Consultant
Terie Norelli (D) - Ex-State House Speaker & Ex-Teacher
Chris Pappas (D) - Executive Councilor & Restaurant Owner
Stefany Shaheen (D) - Ex-Portsmouth City Councilor, Businesswoman & Ex-Management Consultant
Lincoln Soldati (D) - Ex-Somersworth Mayor & Ex-Strafford County Attorney
Donna Soucy (D) - State Sen., Ex-State Rep., Ex-Manchester Alderman & Attorney
Maura Sullivan (D) - Ex-US Asst Secretary of Veterans Affairs & Iraq War Veteran
Marchand is running for Governor, so it'll be interesting to see if he sticks with that or jumps in to this race.
Not to beat a dead horse, but to everyone mention Ayotte earlier -- she indeed lives in Nashua which is not in this district.