United Auto Workers member Brandi Holmes shivers in a slow drizzle as Team 24 pickets outside a truck entrance to Stellantis Toledo Assembly Complex on Tuesday, in Toledo, Ohio. Isaac Ritchey/The Blade via Associated Press

DETROIT — The United Auto Workers union says it will announce on Friday how it plans to expand its strike against Detroit’s three automakers.

The union says President Shawn Fain will announce at 10 a.m. Eastern time in a video appearance addressing union members. Additional walkouts will take place at noon Friday without serious progress in contract talks, the union said.

The union went on strike on Sept. 14 when it couldn’t reach agreements on new contracts with Ford, General Motors, and Jeep maker Stellantis.

At first, it targeted one assembly plant from each company, and last week it added 38 parts distribution centers run by GM and Stellantis. Ford was spared the second escalation because talks with the union were progressing.

The union wouldn’t say what action it would take on Friday, reiterating that all options are on the table.

The union is scheduled to meet with GM negotiators Wednesday afternoon, according to two people with direct knowledge of the talks who spoke on condition of anonymity because they were not authorized to speak on the record.

Fain said Tuesday that negotiations were moving slowly and the union would add facilities to the strike to turn up the pressure on the automakers.

“We’re moving with all three companies still. It’s slower,” Fain said after talking to workers on a picket line near Detroit with President Biden. “It’s bargaining. Some days you feel like you make two steps forward, and the next day you take a step back. Things are moving. We just have to see,” he said.

So far the union has let the companies keep making pickup trucks and large SUVs, their top-selling and most profitable vehicles. It has shut down assembly plants in Missouri, Ohio, and Michigan that make midsize pickup trucks, commercial vans, and midsize SUVs, all of which are profitable but don’t make as much money as the larger vehicles.

Marick Masters, a business professor at Wayne State University in Detroit, said Wednesday that the union is likely to go after the pickup and SUV factories as it tries to squeeze the companies into making better offers. It also could shut down selected component factories such as transmissions which would eventually force the companies to halt assembly plants.

Masters doesn’t think Fain will announce that the whole union will go on strike yet. “I think he probably wants to give himself one or two more moves beyond this,” Masters said.

Fain also is likely to limit the strikes at companies where negotiations are progressing, but escalate them further at companies where talks are moving more slowly, Masters said.

In past years the union has picked one company as a potential strike target and reached a contract agreement with that company that would serve as a pattern for the others.

But this year Fain introduced a new strike method of targeting only part of the companies’ plants, with plans to add more to get the automakers to raise their offers.

Currently, only about 12% of the union’s 146,000 workers at the three automakers are on strike, allowing it to preserve a strike fund that was worth $825 million before Sept. 14.

If all of the union’s autoworkers went on strike, the fund would be depleted in less than three months, and that’s without factoring in health care costs.