The United Auto Workers union endorsed Democratic presidential candidate Kamala Harris on Wednesday, shoring up labour support for her campaign and giving her a near-complete lock on a crucial voting bloc for the party.

The Detroit-based union, which has about 370,000 members, said Harris’s “historic candidacy” would build on the Biden administration’s record of “delivering major gains for the working class”, handing her the support of one of the US’s most politically important unions ahead of November’s presidential election.

“We stand at a crossroads in this country,” UAW president Shawn Fain said in a statement. “We can put a billionaire back in office who stands against everything our union stands for, or we can elect Kamala Harris who will stand shoulder-to-shoulder with us in our war on corporate greed.”