WASHINGTON — Hillary Rodham Clinton’s presidential campaign has picked up the endorsement of the National Education Association, the nation’s largest labor union.

The NEA has 3 million members, and its backing gives Clinton a boost in her competitive Democratic primary race against Vermont Sen. Bernie Sanders. The announcement caps a week in which Sanders announced he had raised nearly as much money as Clinton during the past three months.

The union calls Clinton a “strong leader who will do what is best for America’s students.”

The former secretary of state has won eight labor endorsements representing about 7 million workers, including the nation’s two main teachers’ unions.

The American Federation of Teachers endorsed Clinton during the summer.