Fain told workers during a Facebook Live event that negotiations have not broken down, but "unfortunately, despite our willingness to negotiate, Ford and GM have refused to make meaningful progress at the table."
More than 7,000 workers at GM's Delta Township plant in Lansing, in the U.S. state of Michigan, and at Ford's assembly plant in Chicago, Illinois, will join the strike.
The GM plant has more than 2,800 employees who manufacture large crossover SUVs such as the Buick Enclave and Chevrolet Traverse, while the Ford plant has 5,700 hourly workers who manufacture the Ford Explorer and Explorer police interceptors, as well as the Lincoln Aviator SUV.
Explainer: UAW expands strike against GM, Ford in Week 3, spares Stellantis!
The UAW union on Friday expanded its coordinated U.S. strike, this time targeting a plant at General Motors and Ford Motor but refraining from an additional walkout from Chrysler parent Stellantis.
With the integration of these additional members into the strike, the total number of UAW members on strike at the three automakers will reach more than 25,000.
Stellantis NV is spared this time from the strike extension following progress made in negotiations, Fain said. Last week, the UAW excluded Ford from a strike extension, noting that there was progress at the bargaining table with the automaker.
The UAW announced its strike at three selected Ford, GM and Stellantis factories on Sept. 14, after its contract with the big three manufacturers expired. By Sept. 22, it extended the strike to 38 GM and Stellantis parts distribution centers across the country after failing to make significant progress in new contract negotiations.
According to the latest updates from the company and the union, Ford has offered a 20 percent wage increase over the four-year contract term, the job security sought by the UAW, restoration of cost-of-living adjustments, an improved profit-sharing formula, elimination of a tiered wage, immediate conversion of temporary workers to permanent status, and a reduction from eight to four years in the time it takes permanent full-time workers to reach the top of the wage scale.
GM and Stellantis have made similar wage offers. The union initially demanded a 46 percent increase in compounded pay over four years and has been reducing the request to 36 percent without compounding.