Democratic front-runner Hillary Clinton has snagged another major union endorsement. The American Federation of State, County and Municipal Employees, the largest union of public employees in the United States, endorsed the former secretary of state Friday, CNN reported.

The endorsement came after the group’s 35-person national board, which is elected by union members, voted to back Clinton Friday. "The next president will make decisions that could make or break the ability of working people across America to sustain their families. That's why we spent the last six months engaged in the most member-focused, in-depth, and transparent endorsement process AFSCME has ever undertaken," union President Lee Saunders said, according to CNN.

Unionwide polls influenced the decision, according to CNN’S Dan Merica. Saunders told CNN that the union took three surveys to determine which candidates the members favored. Nearly two-thirds of AFSCME members said they would vote for Clinton in the Democratic primaries.

"Members want a candidate who will make it easier instead of harder to join together in strong unions and stand together for wages and benefits that can sustain our families," Saunders said. "What we also heard was AFSCME members want the candidate who will be the most effective champion for working families, and who will be able to deliver a victory in this critically important election. AFSCME members believe that candidate is Hillary Clinton.”

The union has talked to all Democratic candidates, including Clinton, Vermont Sen. Bernie Sanders and former Maryland Gov. Martin O’Malley. Those three participated in town halls with the union in Iowa earlier this year.

The AFSCME endorsement comes as a big win for Clinton, who has been vying with Sanders for the support of labor unions across the country. Earlier this month, Clinton also received the endorsement of the National Education Association, the nation’s largest teachers union.

Clinton has been having a good week after Vice President Joe Biden decided Wednesday he would not enter the 2016 presidential race and she cleared the hurdle of her testimony in front of the House Select Committee on Benghazi Thursday. The former secretary of state maintains her lead over Sanders nationally, and has opened up an 11-point lead over him in crucial Iowa, beating him 51 percent to 40 percent, according to a Quinnipiac University poll out Friday.

With this most recent endorsement, Clinton will get support from the 1.6-million member union on the ground. State chapters of AFSCME are not required to endorse her, but the national organization will provide financial resources to her campaign, union representatives told CNN.

AFSCME has been supportive of Clinton and her husband before. In 2007, it supported her bid for president, and in 1992 it supported Bill Clinton in his successful run.