About 146,000 U.S. auto workers are set to go on strike this week if General Motors, Ford and Stellantis fail to meet their demands for big pay raises and the restoration of concessions the workers made years ago when the companies were in financial trouble.

Shawn Fain, the combative president of the United Auto Workers union, has threatened to strike any of the three companies that hasn’t reached an agreement by the time its contract with the union expires at 11:59 p.m. Eastern time Thursday.

Both sides began exchanging wage and benefit proposals last week. Though some incremental progress appears to have been made, a final agreement could come too late to avoid walkouts by UAW workers at factories in multiple states. Any strike would likely cause significant disruptions for auto production in the United States.