The trade union UAW, which organizes car workers in the USA, is backing Kamala Harris' presidential candidacy.
Union leader Shawn Fain says in a statement that it is the union's "job" in this year's election to defeat Trump.
"We can put a billionaire back in office who opposes everything our trade union stands for, or we can choose Kamala Harris who will stand by our side in the fight against corporate greed", says Fain.
UAW has one million members, both active and retired. It has a strong base in the states of Michigan, Pennsylvania, and Wisconsin.
The car workers' union has previously expressed its support for Joe Biden. Most of its members support the Democrats, but Donald Trump has won some sympathies with his promise to "save the car industry".