UAW President Shawn Fain declined to comment Monday on reports the union may endorse Biden's re-election bid this week. Fain sharply criticized former President Donald Trump, who is seeking a return to the White House, telling Reuters the Republican "is pretty much contrary to everything we stand for."

Winning the support of auto workers could be crucial in the November presidential election in battleground states like Michigan.

The Trump campaign did not respond to a request for comment. The White House and Biden campaign did not comment on Biden's planned remarks.

Biden, a Democrat, strongly backs the UAW's efforts to unionize carmakers Tesla, Toyota and other automakers, and joined UAW workers on the picket line in Michigan during the strikes against targeted Detroit Three automakers facilities.

Trump did not visit UAW picket lines but spoke in Michigan at a non-union auto supplier in September, saying then "it doesn't make a damn bit of difference what you get because in two years you're all going to be out of business."

The UAW won record-setting contracts including a 25% increase in base wages with General Motors, Ford and Stellantis. Fain has praised Biden administration officials for helping win those contracts and ensure battery plant workers get higher wages.

In May, Fain said the union was not ready to endorse Biden for a second four-year term, citing concerns about EV policies.

Trump has criticized Fain and the Biden administration's EV policies, saying they threaten autoworkers' jobs, while the Biden administration has touted more than $150 billion in new planned electric vehicle and battery plant investments.

The UAW and major automakers have urged the Environmental Protection Agency to soften proposed 2032 vehicle emissions regulations that would result in 67% of new vehicles being EVs.

Fain told Reuters Monday the union has been "very vocal" about its views on the regulations.

"They know where we stand," Fain said.

The EPA sent the plan to the White House last week for review.

(Reporting by David Shepardson; Editing by Chizu Nomiyama and Deepa Babington)

By David Shepardson