The UAW will expand its strike against the Detroit 3 on Friday if negotiations this week stall, President Shawn Fain said.

“If we don’t make serious progress by noon on Friday, Sept. 22, more locals will be called on to stand up and join the strike,” Fain said in a video posted by the union Monday evening. “Autoworkers have waited long enough to make things right at the Big 3. We’re not waiting around and we’re not messing around.”

Fain didn’t say how many additional plants would join the work stoppage, which began Friday. His comments suggested that the UAW could decide not to add plants even without deals in place by Friday, so long as the union is satisfied that the talks are productive.

About 13,000 workers at three plants — one each from General Motors, Ford Motor Co. and Stellantis — are currently on strike and would become eligible for strike pay from the union on the day of Fain’s next announcement.

After the strike began, Ford laid off about 600 additional workers in Michigan as a consequence of its reduced production capacity, and GM has said it will need to lay off about 2,000 workers in Kansas as early as this week.

Negotiations continued Monday, although Fain has called progress “slow.” A person with knowledge of the talks said the union has not received any new proposals from the automakers since the strike began.

Fain told NPR earlier Monday that “the ball’s in their court,” referring to the companies.

Bargaining at the subcommittee level continues at a near constant pace while the union has held main table discussions with each company since the strike began. It met with Ford on Saturday, GM on Sunday and Stellantis on Monday.

In a statement, Stellantis said “the discussion was constructive and focused on where we can find common ground to reach an agreement that provides a bridge to the future by enabling the Company to meet the challenges of electrification.” It said the two sides “have the opportunity to establish a framework in this contract that will allow the company to be competitive during this historic transformation and bring our workforce along on this journey. This includes identifying a solution for Belvidere, something we have been committed to from the beginning and a discussion we want to continue with the UAW.”

Stellantis’ Belvidere Assembly Plant in Illinois has been idled since February. The company said its most recent proposal to the union provided a solution for the plant.

It was unclear when the companies plan to present counteroffers to the union. Each offer on the table includes 20 percent wage gains over four years and reduces the time it takes for new hires to reach top wages from eight years to four.

Meanwhile, Ford continues to face the threat of dual strikes in the U.S. and Canada. It was continuing to negotiate with the Unifor union in Canada ahead of an 11:59 p.m. Monday deadline.

A strike there could affect 5,600 workers at one assembly plant and two engine plants and quickly have a ripple effect on U.S. operations. The two engine plants built V-8s that power Ford’s lucrative Super Duty pickups, F-150s and Mustangs.