(Bloomberg) -- The United Auto Workers union plans to expand its strike against Detroit’s legacy automakers on Friday if there isn’t major progress in negotiations.

The announcement would be made Sept. 29 at 10 a.m. Detroit time in a Facebook Live event hosted by UAW President Shawn Fain, the union said. The deadline for a strike expansion would be noon that day.

On Sept. 15, the UAW began a walkout at plants operated by General Motors Co., Stellantis NV and Ford Motor Co. — the first time all three carmakers were targeted at the same time. A week later, the union expanded the strike to 38 more GM and Stellantis plants. Ford was spared an escalation after making progress in the negotiations.

A person familiar with the negotiations said that union representatives expected to meet with GM negotiators at 4:00 p.m. Wednesday, though no immediate meetings with Ford or Stellantis were planned. 

The union’s strike strategy is to remain flexible and respond to what is happening at the bargaining table, the person said. Asked whether Ford will still be spared in a next round of strikes, the person’s response was everything is on the table.

The union is expected to release a video highlighting violence some strikers have experienced on the picket line. On Tuesday afternoon in Flint, Michigan, someone driving a dark colored Chevrolet HHR sport utility vehicle was attempting to exit GM’s service and parts operation was blocked by picketers, according to the Metro Police Authority of Genesee County. The driver then drove though the picket line and hit five people; one person was taken to a local hospital. Police are in the process of identifying the driver. 

Earlier Wednesday, US Secretary of Transportation Pete Buttigieg reiterated Joe Biden’s message that the auto companies’ record profits should be shared as record pay for their workers. 

“This is something that can benefit the entire auto sector too,” he told MSNBC. “When you have well-paid workers with good benefits, that also is consistent with a US auto sector that is thriving.”

--With assistance from Keith Laing.

(Updates with GM meeting timing, other comments from the fifth paragraph)

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