The UAW on Wednesday endorsed President Biden for re-election, ending its months-long holdout over concerns about his EV policies.

Why it matters: With about 1 million members, including active and retired workers, the UAW remains a powerful force in progressive politics.

Driving the news: UAW president Shawn Fain hailed Biden's leadership, praising the president for standing with the union during its strike against the Detroit Three automakers.

• "This choice is clear," Fain said. "Joe Biden bet on the American worker, while Donald Trump blamed the American worker."
• "Donald Trump is a scab!" he added to raucous cheers at a UAW political conference in Washington, D.C.

Context: The endorsement came after the UAW scored record contracts from General Motors, Ford and Stellantis following an unprecedented simultaneous strike against all three automakers.

• During the strike, Fain said the White House was "afraid" of the union's momentum, and personally challenged Biden to join the picket line.
• Biden quickly accepted the invitation and appeared alongside Fain on a picket line outside a GM facility in Michigan in September.
• He made another appearance with Fain after the UAW landed new contracts — but he still didn't get the endorsement.

What they're saying: "I'm honored to have your back," Biden said, briefly donning a UAW hat, adding that "I was so damn proud to stand in the picket line with you."

Yes, but: The UAW was never expected to consider endorsing former President Trump, whom Fain has repeatedly lambasted.

• Still, the union had expressed concern over the federal government doling out EV incentives for vehicles made by foreign automakers without union labor.

Worth noting: The UAW's membership base is not politically monolithic.

• About one-third of its members voted for Trump in 2016 and 2020, according to the union's internal polling.

What we're watching: Whether the endorsement affects the UAW's prospects of organizing the non-unionized automakers in the U.S.

• Many of them, including Volkswagen, Toyota, Mercedes-Benz and Hyundai, are in the more politically conservative South.

Editor's note: This story was updated with Biden's comments from the event.