UAW President Shawn Fain said in a statement that the union’s “job” in this year’s election was to defeat Trump. The union has more than a million active and retired members with a strong base in what the Democrats call the “blue wall” states of Michigan, Pennsylvania and Wisconsin.

“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,” Fain said.

There was never any doubt that the UAW would endorse Harris after President Joe Biden dropped out of the presidential race. Biden won the UAW’s backing in January, and accepted it with a speech at a union political convention in Washington. The AFL-CIO, the umbrella labor organization that includes the UAW, had already endorsed the vice president.

Fain needed to wait for the union’s executive board to give the nod to Harris, but has repeatedly attacked Trump ahead of the endorsement.

“There is only one answer to the threat we face as a nation, and it’s not another billionaire in office,” Fain wrote in a UAW post early Wednesday on the X social media site.

Fain and the union also have called Trump a “scab,” a derogatory term for workers who cross union picket lines and work during a strike. They also have said he did nothing for workers in Ohio when General Motors closed a factory in 2019.

The UAW endorsed Biden’s reelection bid in January, just a few months after the Democratic president joined striking General Motors workers on the picket lines near Detroit. The union won big raises last fall after limited strikes at all three Detroit automakers.

Shortly after the Biden endorsement, Fain was making multiple television appearances on Biden’s behalf. But those waned as the UAW ramped up its campaign to organize nonunion auto factories and a spat with a court-appointed union monitor.

The UAW says its union members and retirees typically lean toward Democrats, but a sizeable number support the GOP. That’s consistent with AP VoteCast, which found that 56% of union members and households backed Biden in 2020, while 42% backed Trump.

Still, Trump has courted union members, saying when he accepted the Republican nomination that he would rescue the auto industry from what he called “complete obliteration.”

He also called for members to fire Fain, using false claims that Fain allowed Chinese automakers to build auto factories across the border in Mexico to ship electric vehicles to the U.S. without tariffs. Industry analysts know of no such factories under construction. The auto industry is currently far from obliteration. Detroit auto companies are still making billions and auto manufacturing employment is up 13.8% since Biden took office.

Trump said he would put tariffs on Chinese-made electric vehicles. Biden earlier this year slapped tariffs on Chinese imported goods, including EVs.

The 1.3 million-member Teamsters union, whose president spoke at the Republican National Convention, has yet to make an endorsement in the race.