The targeted actions against selected auto plants would be the United Auto Workers' first-ever simultaneous strike against the Detroit Three carmakers.
GM reported a $3.6 billion pre-tax loss in 2019 after the 42-day walkout.
Ford Motor has proposed a 20% hike in pay over the contract term. General Motors previously proposed a 18% hike, and Chrysler parent Stellantis (STLAM.MI) 17.5%, Fain said Wednesday. That is less than half the pay hikes the union has sought, but higher than companies' initial offers. It is not clear what is in the new GM offer.
Ford said Thursday it was still waiting for a UAW counteroffer.
Ford warned of a grim scenario. "The future of our industry is at stake. Let's do everything we can to avert a disastrous outcome."
The union's demands include restoring defined benefit pensions for all workers, 32-hour work weeks and additional cost-of-living hikes, as well as job security guarantees and an end to the use of temporary workers.
The UAW said it was planning a rally in Detroit on Friday that will include Fain, Senator Bernie Sanders and other members of Congress, coinciding with a first of day of expected walkouts.
How long will the strike's impact on the U.S. economy and GDP last?