United Auto Workers (UAW) president Shawn Fain threatened the big three automakers with further strikes starting Friday if the companies don’t make “serious progress” on negotiating a contract.

UAW began a historic strike against Ford, General Motors and Stellantis last Friday. The union is demanding higher wages, shorter work weeks, union representation for battery plant workers and better retirement benefits, including restored pensions for new hires.

“Our members have been clear about their demands, and we know the companies can afford to make things right. Record profits mean records contracts,” Fain said in a video message Tuesday. “We’ve been available 24/7 to bargain a deal that recognizes our members’ sacrifices and contributions to these record profits.”

“If we don’t make serious progress by noon, on Friday, September 22, more locals will be called on to stand up and join the strike,” he continued.

The union has called on a few locals to strike at a time instead of pushing for a mass walkout, with Fain saying the strategy is meant to “keep the companies guessing.” Last week, workers from plants near St. Louis, outside Detroit and in Toledo, Ohio, walked out.

On Saturday, Fain turned down a new offer from Stellantis, which would have provided for a 21 percent wage increase. The union has demanded 40 percent raises over the course of a contract, citing inflation’s toll on worker pay and the companies’ increasing profits.

Profits at the big three automakers collectively increased by about 92 percent in the last decade, according to an analysis released last week. CEO pay rose by about 40 percent in the same period.

The Biden administration has backed the strike, with the president calling on the companies to increase their offers.

“I believe they should go further. … Record corporate profits, which they have, should be shared by record contracts for the UAW,” Biden said last week.

Fain emphasized that UAW workers from all over the country are prepared to strike on short notice if called upon.

“Either the big three get down to business and work with us on negotiations, or more locals will be called on to stand up and go out on strike,” he said.