Warren praised El-Sayed for "not taking corporate money" and called out the "special interests running millions of dollars in TV ads to buy this seat."
"Despite the onslaught of outside corporate money spent against us, we have shown that working people are ready for change," said the congressional hopeful.
In what could be his most important endorsement in the tight Senate primary, Michigan's largest and most influential union said El-Sayed was "someone we can trust to have our backs."
Veterans in the labor movement have played a frontline role resisting Trump administration attempts to cut government jobs and services and strip federal workers of their collective bargaining rights.
