The Hawaii State Teachers Association has endorsed U.S. Rep. Mazie Hirono for U.S. Senate.

The teachers union, which represents about 13,000 teachers statewide, said Hirono has been “an unwavering champion of education and labor. She supports many of the educational tenets we believe in and understands that funding and support for teachers is a critical part of Hawaii’s future.”

Hirono, who is running against former congressman Ed Case in the primary to replace retiring U.S. Sen. Daniel Akaka, D-Hawaii, had previously picked up the endorsements of two other major public-sector labor unions, the Hawaii Government Employees Association and the United Public Workers. Case was endorsed by the University of Hawaii Professional Assembly.

Former Gov. Linda Lingle, the leading Republican candidate for Senate, has been endorsed by the State of Hawaii Organization of Police Officers.

The HSTA has also endorsed former Honolulu Mayor Mufi Hannemann in the 2nd Congressional District and U.S. Rep. Colleen Hanabusa in the 1st Congressional District.

Hannemann is facing Honolulu City Councilwoman Tulsi Gabbard, Office of Hawaiian affairs chief advocate Esther Kiaaina, Hilo attorney Bob Marx and Honolulu attorney Rafael del Castillo in the Democratic primary.

Hanabusa has a likely general election rematch with former congressman Charles Djou, a Republican.

“This is an important time to plan for Hawaii’s future and the many challenges we face. With a strong congressional delegation, we will have leaders that will be a strong voice for Hawaii’s children and working families,” HSTA President Wil Okabe said in a statement.