Updated at 3:55 p.m. ET.
The nation's largest public-employee union is backing Hillary Clinton for president. The board of the American Federation of State County and Municipal Employees voted to endorse the former senator and secretary of state on Friday.
"AFSCME members want a candidate who is committed to fixing our out-of-balance economy and raising incomes for hardworking people, who are still struggling to make ends meet," said AFSCME president Lee Saunders in a statement.
Clinton said in a statement of her own that she was "honored" to get AFSCME's endorsement and will "stand with them in the fight to help working families get ahead and stay ahead."
And she was clear who they were fighting.
"Now, working families are under attack by Republicans who want to silence workers, strip them of their hard-won rights, and keep stacking the deck for those at the top," Clinton said. "As [p]resident, I will stand up for workers and fight attacks on collective bargaining. I will fight to protect retirement security, including defined benefit plans and Social Security — because when unions are strong, families are strong, and when families are strong, America is strong."
With more than 1.5 million members, AFSCME is an important endorsement for Clinton and a blow to her chief Democratic rival, Vermont Sen. Bernie Sanders.
"Bernie is proud to have the grass-roots support of tens of thousands of working families in AFSCME and other unions," said Michael Briggs, a Sanders spokesman.
AFSCME also endorsed Clinton during her first bid for president in 2007 over rivals Barack Obama and John Edwards.
Many unions are still deciding which candidate to back in 2016. The large and influential American Federation of Teachers backs Clinton, but the National Nurses United endorsed Sanders in August. Labor's biggest umbrella organization, the AFL-CIO has yet to endorse.
Saunders said that the union polled members over the past six months and that two-thirds said they would vote for Clinton in the Democratic primaries. He also cited her commitment to higher wages, paid family and sick leave and retirement security.