The United Auto Workers union (UAW) said it would expand its strike at noon on Friday if talks with Detroit's Big Three automakers fail to make "significant progress." "Either the Big Three get down to business and work with us to make progress in negotiations, or we're going to call on more local workers to step up and strike," UAW President Shawn Fain said in a video posted on Facebook.

A union representative said earlier that General Motors, Ford Motor and Stellantis NV have not come up with new plans since the UAW made its contract request on September 14. Some factories of these three major automobile companies have been on strike since September 15.

Stellantis released an update on the bargaining situation between the two parties on September 16, which was described by some media as a new plan. But according to a person familiar with the contract negotiations, the latest plan was proposed by the UAW. The person spoke on condition of anonymity because internal discussions are private.

Stellantis issued a statement via email on Monday, saying it had resumed negotiations and had "constructive" discussions with union representatives to focus on the "common ground" between the two sides. The company said it offered a nearly 21% wage increase and pledged to work to find a solution for a shuttered Jeep factory in Belvidere, Illinois.

Over the weekend, the company's chief negotiator had said proposals surrounding the Belvidere plant were no longer on the table after the UAW rejected its latest proposal ahead of a strike deadline.

On Sunday, UAW President Fain rejected Stellantis' offer for a 21% salary increase, saying it was "absolutely not feasible."

Sources said that under Stellantis' plan, 18 facilities may be closed, including parts and distribution centers. The company's North American headquarters and technology center in Detroit may also be affected.

The UAW launched a general strike on September 15, minutes after its original contract with the automaker expired. Nearly 13,000 workers are on strike at a Ford plant in Michigan that makes the Bronco SUV, a General Motors plant in Missouri that assembles the Chevrolet Colorado pickup truck and a Stellantis plant in Ohio that makes the Jeep Wrangler.

General Motors and Ford have announced layoffs for some workers not involved in the strike, citing spillover effects from the strike action. According to people familiar with the matter, the UAW will pay these workers the equivalent of strike wages of $500 per week, even though they are not participating in the strike. The UAW has an $825 million strike fund.

The UAW declined to disclose the specifics of its latest demands, but the auto companies said the union had lowered its demand for a pay increase from 40 percent to 36 percent. General Motors and Ford each proposed a 20% wage increase, but the UAW rejected it. People familiar with the matter said that the latest plan given by Stellantis is a salary increase of 19.5%. If compound interest during the entire contract period is included, it will be 21%.