The Hawaii Government Employees Association, the state’s largest public-sector labor union, has endorsed U.S. Rep. Mazie Hirono in the Democratic primary for U.S. Senate.

Hirono is facing former congressman Ed Case in the primary to replace U.S. Sen. Daniel Akaka, D-Hawaii, who is not seeking another term. Former Gov. Linda Lingle is considering a Republican campaign for U.S. Senate.

“Throughout her career, Mazie Hirono has been a strong voice for working families — which is why we are proud to recognize her with our early endorsement,” Randy Perreira, the HGEA’s executive director, said in a statement. “We are confident that she will work well with Senator Daniel Inouye and together they will continue to make invaluable contributions to our state that will benefit us for many years to come.”

Labor leaders have sought to build a “solid front” for Hirono. The Hawaii State AFL-CIO, an umbrella federation for dozens of labor unions, endorsed Hirono earlier this month. Perreira is also the president of the Hawaii State AFL-CIO.

Case has said he is comfortable taking his campaign message directly to rank-and-file union members.