The Service Employees International Union endorsed Hillary Clinton for President of the United States today. 

The union, which has two million members, is an important source of money and manpower as Clinton marches toward the Democratic nomination. 

SEIU promises "hundreds of thousands of face-to-face and door-to-door contacts, millions of phone calls, robust digital engagement and other activities to get out the vote." 

Locking down the SEIU endorsement is a significant victory for Clinton, whose relationships with organized labor has been mixed during her long career in public life, going back to Arkansas when she was on the board of Walmart, known for its hostility to organized labor. 

SEIU has been closely aligned with the so-called "Fight for $15" campaign to raise wages to at least $15 per hour. Clinton has called for $12 minimum wage.