Shawn Fain, president of the United Auto Workers union (UAW), on Monday night announced that more locations may be called to join the union’s strike on Friday.

The UAW declared a historic strike against all three members of the Big Three automakers at midnight Thursday, after contracts expired with Ford, General Motors and Stellantis.

“I have been clear with the Big Three every step of the way, and I’m going to be crystal clear again right now. 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 to social media.

Instead of striking all plants at once, the union is holding a “Stand Up Strike,” where select facilities will be called on to walk out on strike. Workers who are not called to strike will continue working under the agreement.

Workers at the Ford Michigan Assembly Plant in Wayne, the Stellantis Toledo Assembly Complex in Ohio, and General Motors’ Wentzville Assembly in Missouri were the first facilities called to strike last week.

The potential announcement of additional strikes will mark more than a week since members first walked out, and a week of the Detroit Three “failing to make progress in negotiations,” Fain said.

“Noon on Friday, Sept. 22 is a new deadline. Either the Big Three get down to business and work with us to make progress in negotiations, or more locals will be called to stand up and go out on strike,” Fain said.

State and national politicians have come out to support union workers, including U.S. Sen. Bernie Sanders?(I-Vt.), Gov. Gretchen Whitmer, U.S Rep. Debbie Dingell (D-Ann Arbor), U.S. Sen. Gary Peters (D-Bloomfield Twp.) and U.S. Sen.?John Fetterman?(D-Pa.).