When Hillary Clinton bagged an endorsement from the Service Employees International Union on Nov. 17, she secured more than just the symbolic support of one of the nation's most influential labor organizations.

SEIU's decision to back her over Vermont Sen. Bernie Sanders means she will get millions of dollars, thousands of volunteers and hundreds of targeted ads for her presidential campaign, courtesy of Big Labor.

SEIU's revenue last year topped $321 million, and it's ready to spend a big chunk of that to get Clinton into the White House.

Beyond money and donations, the union controls another key weapon in Clinton's arsenal: Amalgamated Bank, an institution rapidly becoming the Left's financier of choice.

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