The United Auto Workers (UAW) union is expanding a strike at some of America’s biggest car firms, sending the row over pay and benefits into its third week.
Union boss Shawn Fain said 7,000 more staff at Ford and General Motors factories are set to walk off the job.
The latest action did not target Stellantis, reflecting new momentum in those talks, he said.
Roughly 18,000 workers were already on strike in a dispute that has cast a cloud over the US economy.
US President Joe Biden and former President Donald Trump, who is running for re-election, both visited the Detroit area this week to address the issue, which comes as labour tensions simmer across the country.
The union opened talks seeking a roughly 40% rise in pay over four years and an end to practices that give newer hires lower pay and fewer benefits, among other demands.
The companies have maintained that the union’s demands would hurt their ability to invest in the long term. They have countered with a roughly 20% pay increase and some other concessions.
UAW boss Mr Fain urged his roughly 150,000 members working at the three carmakers to hold strong as the talks continue.
“Our cause is just. Striking… to protect our communities and to defeat corporate greed is not just our right – it is our duty,” he said.
For now, workers on the picket line in the Detroit area this week said they remained committed to the fight, despite the loss of income for many that will come from receiving just $500 (£410) in strike pay a week.
“People are fed up. We want there to be a middle class,” said Emily Yettaw, who has worked at GM for 17 years. “They’re making billions in profit and we deserve better.”
