Blue Mass. Group runs down prospective candidates for the 3rd Suffolk seat just vacated by Sal DiMasi. So far, the only "official" candidate (new House Speaker Bob DeLeo has yet to set an election date) is Aaron Michlewitz of the North End (Facebook page), DiMasi's constitutent-services director, who filed organization papers with the state on Wednesday and who opened his campaign office today on Endicott Street in the North End.

Other possibilities: Lucy Rivera (former aide to Tom Birmingham and Michael Capuano), Susan Passoni (who ran against Jimmy Kelly for Boston City Council), both of the South End, and Stephen Passacantilli, of the North End, who is currently an aide to City Councilor Sal LaMattina.