The United Automobile Workers union on Friday significantly raised the pressure on General Motors and Stellantis, the parent of Jeep and Ram, by expanding its strike against the companies to include all the spare parts distribution centers of the two companies.
Shawn Fain, the union’s president, said Friday that workers at 38 distribution centers, which provide parts to dealerships for repairs, at the two companies would walk off the job at noon. He said talks with two companies had not progressed significantly, contrasting them with Ford Motor, which he said had done more to meet the union’s demands.
“We will shut down parts distribution centers until those two companies come to their senses and come to the bargaining table,” Mr. Fain said.
The affected locations include 18 G.M. distribution centers that employ a total of 3,475 workers, and 20 Stellantis centers with 2,150 U.A.W. members, according to the union. The move brings the total number of striking U.A.W. workers to more than 18,000.
Representatives for G.M. and Stellantis did not immediately provide comments on the strike’s expansion.
The union said it was not striking more facilities at Ford because of the gains it had achieved in talks with that company, including on cost-of-living adjustments, the right to strike if the company decides to close plants and two years of pay and health care benefits for workers who are laid off indefinitely.
“To be clear, we are not done at Ford,” he said. “We have serious issues to work through, but we do want to recognize that Ford is serious about reaching a deal.”
Ford said in a statement that it was “working diligently” to reach a deal but said the company and union were still far apart on issues like wages. “Although we are making progress in some areas, we still have significant gaps to close on the key economic issues,” the company said. “In the end, the issues are interconnected and must work within an overall agreement that supports our mutual success.”
In his remarks, which were broadcast live on Facebook, Mr. Fain also invited President Biden to join workers on the picket line. Mr. Biden strongly supported U.A.W. members in remarks at the White House last week. But the union has at times expressed unease with the president’s policy on electric vehicles and has withheld its endorsement in the 2024 presidential race. The union usually endorses the Democratic candidate.
Tensions between the union and the automakers had flared up even before Mr. Fain announced the expansion of the strike. On Thursday, private messages sent by a union communications manager through X, formerly known as Twitter, seemed to suggest that the union leaders were pleased that the strike appeared to be hurting the three manufacturers.
Jonah Furman, who was hired to direct the U.A.W.’s media relations after Mr. Fain took office this year, wrote in the messages that the strike was causing the automakers to suffer “reputations damage and operational chaos.”
The contents of the messages were revealed in The Detroit News.
G.M. said in a statement that the leaked messages showed a “callous disregard for the seriousness of what is at stake” in the strike.
“It’s now clear that the U.A.W. leadership has always intended to cause monthslong disruption, regardless of the harm it causes to its members and their communities,” the company added.
The U.A.W. declined to comment.
The expansion of the stoppage heightens the stakes for both sides, and could force other plants owned by the automakers and their suppliers to halt production.
The union is paying striking workers $500 per week each from its $825 million strike fund, while the manufacturers are faced with losing tens of millions of dollars in revenue every day that the affected plants remain idled.
A week ago, the union called on workers to strike at a G.M. pickup truck plant in Wentzville, Mo.; a Ford factory in Michigan that makes the Bronco sport-utility vehicle; and a Jeep plant in Toledo, Ohio, owned by Stellantis.
The union is seeking a substantial increase in wages, noting that the automakers have reported strong profits in the last 10 years and have raised the pay of their chief executives. The union initially demanded a 40 percent increase; the companies have offered about 20 percent over four years.
The U.A.W. also wants more workers to qualify for pensions, company-paid retiree health care, shorter working hours and job security for workers if the manufacturers close plants in the future. It also wanted to end a wage system in which new hires start at about $17 an hour, and must stay on the job eight years to climb up to the top wage of $32 an hour.
Peter Berg, a professor of employment relations at Michigan State University, said the U.A.W.’s strategy of limiting strikes to certain locations eases the cost of supporting workers from its strike fund, but hurts the manufacturers because those plants make some of their most profitable vehicles.
“The question is, can the union maintain solidarity and keep everyone together if this continues for several more weeks,” he said.
Earlier in the week, workers demonstrating at Stellantis’s North American headquarters in Auburn Hills, Mich., said they were energized and ready to join the walkout, if called to do so.
“President Fain has got fight,” said Marnice Alford, who works in the paint shop at a Stellantis plant in Sterling Heights, near Detroit. “I like that.”
Santul Nerkar contributed reporting.