As the United Auto Workers strike enters its fourth week, Ford’s Chicago Assembly Plant is set to take center stage in the ongoing labor dispute against the Big Three automakers.

UAW President Shawn Fain is planning to bring the fight and focus to Chicago at a rally Saturday to support 4,600 striking workers who walked off the job last week at the Ford plant, which makes the Ford Explorer, Lincoln Aviator and Police Interceptor SUVs. The Explorer, which is built exclusively at the century-old Torrence Avenue plant on the city’s Southeast Side, is among Ford’s best-selling vehicles.

The rally is scheduled for 2 p.m. at the adjacent headquarters of UAW Local 551, which represents the Ford assembly workers.

“We’re at war,” Chris Pena, president of UAW Local 551, said Friday. “We’ve got Fain coming tomorrow to lift people’s spirits. It’s going to be a game changer to see someone they elected be on the front lines.”

The UAW, which represents 146,000 members across the U.S., is seeking a new four-year labor agreement with General Motors, Ford and Stellantis. Demands include pay increases, shorter workweeks and improvements to retiree pensions and health care plans amid record profits for the Big Three automakers.

When the previous contract expired on Sept. 15, the UAW launched a strike against all three automakers for the first time in the Detroit-based union’s 88-year history. The strike has since expanded to 25,000 UAW members at 43 facilities in 21 states.

During a Friday online address to UAW members, Fain said plans to strike against GM’s Arlington Assembly plant in Texas, which builds full-size SUVs such as the Chevy Tahoe and GMC Yukon, were called off at the last minute when the automaker agreed to cover EV battery workers under the labor agreement.

“This week, GM did something that was unthinkable until just today: They agreed to put the future of this industry under our national agreement,” Fain said. “This victory is the direct result of the power of our membership.”

While Fain touted progress in negotiations, he said the Big Three need to continue to move toward a “record” labor contract to avoid more strikes.

The strike at the Chicago Assembly Plant has already had far-reaching effects.

Ford laid off 243 non-striking workers at its stamping facility in Chicago Heights beginning Sept. 30 and another 90 at a Lima, Ohio, engine plant Monday, both of which supply parts to the idled Chicago Assembly Plant.

The automaker expanded the Chicago-related layoffs on Thursday into two Michigan parts facilities, giving the pink slip to 350 workers at its Livonia Transmission Plant and 50 at the Sterling Axle Plant.

On Friday, Ford told another 495 workers not to report to their jobs Monday at facilities in Michigan and Ohio, including 372 at the Cleveland Engine Plant, due to the production halt in Chicago.

“While we are doing what we can to avoid layoffs, we have no choice but to reduce production of parts that would be destined for a plant that is on strike,” Bryce Currie, vice president of Ford Blue manufacturing for the Americas, said in a news release Friday. “Strike-related layoffs are an unfortunate result of the UAW’s strategy.”

In addition to Ford’s Chicago Assembly Plant, nearly 200 parts distribution workers at a GM center in Bolingbrook and a Stellantis facility in Naperville have been on strike since Sept. 22.

rchannick@chicagotribune.com