The following are the endorsements Senator O'Connor has received during his run for re-election.
Massachusetts Coalition of Police
Massachusetts Police Association
State Police Association of Massachusetts
Tim Cruz, Plymouth County District Attorney
Joe McDonald, Plymouth County Sheriff
Professional Fire Fighters of Massachusetts (PFFM)
Weymouth Fire Fighters Local 1616
Massachusetts Nurses Association
Massachusetts Voters for Animals
Massachusetts AFL-CIO
Mass Retirees
International Union of Operating Engineers Local 4
United Food & Commercial Workers Union Local 328
United Steelworkers Local 12003
Boston Carmen's Union 589
United Brotherhood of Carpenters & Joiners of America Local 346
International Association of Bridge, Structural, Ornamental and Reinforcing Iron Workers Local 7
International Brotherhood of Electrical Workers Local 103
International Brotherhood of Electrical Workers Local 223
International Association of Machinist and Aerospace Workers Local 264
Massachusetts Organization of State Engineers and Scientists
Laborers' International Union of North America- Local 13
Plumbers Local 12 Boston
Sprinkler Fitters and Apprentices Local 550
Sheet Metal Workers' Local 17
American Federation of Teachers- Massachusetts
Boston Teachers Union
Massachusetts & Northern New England Laborers' District Council
Transport Workers Union Local 2054