The Hawaii Carpenters Union today 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 next year. Former Gov. Linda Lingle and attorney and former state lawmaker John Carroll are competing in the Republican primary.

The 6,500-member carpenters union is the state’s largest private-sector construction union.

“There is really no other candidate for us than Mazie,” Ron Taketa, the financial secretary and business representative for the Carpenters Union, said in a statement, said: “Her ideals and concern for the issues that most affect not just our union members, but working people throughout the state, promise the kind of progressive service and cooperation that Hawaii has greatly benefitted from through the years with Senator Akaka on Capitol Hill.”