Speaking at the Democratic National Convention on Monday in Chicago, Shawn Fain, president of the United Automobile Workers, said “the UAW will take whatever action necessary at Stellantis or any other corporation to stand up and hold corporate America accountable.” Paul Sancya/Associated Press

DETROIT — A high-profile spat between the United Auto Workers and Stellantis over reopening an Illinois factory complex has made its way into the presidential race and could elicit a strike against the automaker.

In a speech at the Democratic National Convention on Monday night, UAW President Shawn Fain accused the company of reneging on promises to restart a now-closed assembly plant in Belvidere, Illinois, just over an hour northwest of Chicago.

The union won the reopening in contract talks last fall after a six-week strike at multiple factories run by Jeep and Ram maker Stellantis, as well as General Motors and Ford.

“Let me be clear: Stellantis must keep the promises they made to America in our union contract,” Fain told the crowd at the Chicago convention.

“The UAW will take whatever action necessary at Stellantis or any other corporation to stand up and hold corporate America accountable,” he said, clearly referring to the possibility of a strike.

In a statement Tuesday, Stellantis confirmed that it notified the UAW of plans to delay reopening of Belvidere but said it stands by the commitment and “strongly objects” to union allegations that it’s violating terms of the UAW contract.

“The UAW agreed to language that expressly allows the company to modify product investments and employment levels,” spokeswoman Jodi Tinson said in the prepared statement. “Therefore the union cannot legally strike over a violation of this letter at this time.”

Stellantis said that it is critical that a business case be made for all investments to match market conditions “to ensure the company’s future competitiveness and sustainability, which are necessary to preserve U.S. manufacturing jobs.”

In a grievance filed with the company, the UAW said Stellantis has said that it won’t open a parts distribution hub in Belvidere this year, that it won’t restart metal stamping operations there in 2025, and that it doesn’t plan to begin producing a midsize truck at the plant in 2027.

The delays violate the 2023 contract, the union said, and could last into 2028, after the current agreement expires. In a statement Tuesday, Fain said Stellantis is dragging out the process so it never has to reopen the plant.

“They really want to kick the can past our contract expiration so they can suddenly cite ‘market conditions’ again and never reopen the plant,” Fain said. “If they go back on this, what else can they go back on?”

After the contracts were approved, President Biden visited Belvidere with Fain to celebrate the plant reopening.

Fain has been sharply critical of Stellantis CEO Carlos Tavares for threatening job cuts as the company’s U.S. sales have faltered this year.

U.S.-European automaker Stellantis reported that its net profits fell by half during the first six months of the year largely because of lower sales and restructuring costs.

Fain, wearing a red T-shirt that said “Trump is a scab. Vote Harris,” told the convention that the union won strong contracts and the plant reopening with the support of Biden and Vice President Kamala Harris.

“Scab” is a derogatory term for workers who cross union picket lines and work during a strike.

In a statement Tuesday, Trump’s campaign called Fain a puppet for the Democratic party who is not serving union laborers who support Trump, who the campaign says know “he will protect their jobs and put them first.”

Trump is running again to fix the “economic disaster” caused by failed policies of the Biden and Harris administration, the statement said.