The Hawaii State Teachers Association, which represents roughly 13,000 teachers statewide, today endorsed Democratic gubernatorial candidate Neil Abercrombie. HSTA is the fourth-largest union in the state.

This is the 15th labor organization to publicly support the former congressman — and the third endorsement he has received from an education-related organization. The other two are the University of Hawaii Professional Assembly and the American Federation of Teachers.

The Hawaii Government Employees Association, which at 44,000-strong is the state’s largest labor union and includes many members within the Hawaii Department of Education, has yet to declare its favored candidate.

Other labor organizations endorsing Abercrombie include:

• American Postal Workers Union
• Industrial Technical & Professional Employees Union
• International Brotherhood of Boilermakers
• International Brotherhood of Electrical Workers (Local 1186, Local 1260, Local 1357)
• International Longshoremen’s Association
• Laborer’s International Union (Local 368)
• National Air Traffic Controllers Association
• Seafarers’ International Union
• Transportation Communications International Union
• UNITE HERE! Local 5
• United Association of Plumbers & Pipefitters
• United Food & Commercial Workers Union

Democratic candidate Mufi Hannemann has received 12 labor union endorsements so far, including one from the United Public Workers, which counts some education department workers among its members.

Read more about labor union endorsements thus far in the gubernatorial race here.