The United Auto Workers' strike against the Big Three U.S. automakers spreads as the strike entered its 20th day on Wednesday.

The union is expected to give a Facebook Live update on Friday on its bargaining with the Big Three to its members. It's unclear if it plans to expand the strike then.

Ford Motor Co. is directing 350 workers at its Livonia Transmission Plant and 50 at the Sterling Heights Axle Plant not to report to work on Thursday, according to a statement sent by Ford spokesperson Dan Barbossa on Wednesday. The layoffs are a result of the expansion of the strike at Ford's Chicago Assembly Plant last week, which produces Ford Explorer, Lincoln Aviator, and Police Interceptor SUVs.

Ford has laid off roughly 1,330 workers since the union strike started on September 15.

On Tuesday, Ford made its seventh and "strongest" offer to the union, including product commitments for every UAW-represented plant in the country, an increase in starting pay for temporary workers to $21 per hour, conversion upon ratification of all temporary workers with at least three months of continuous service and a wage increase of "more than 20 percent."

The offer also includes restoring cost-of-living allowances, eliminating wage tiers, reducing by "more than half" the time it takes workers to reach the top of the wage scale.

Stellantis was spared from strike expansion last week as it made progress in talks with the union on areas, including cost-of-living adjustments, the right not to cross a picket line, the right to strike over product commitments and plant closures and an outsourcing moratorium.

With 9,200 UAW member workers on strike, General Motors (GM) has laid off 2,175 at its plants that feed those facilities or require parts from them. The Detroit-based automaker estimates the strike has affected another 2,500 workers at its suppliers.

In a new filing with the Securities and Exchange Commission on Wednesday, GM said the UAW strike has cost it $200 million as of late September.

It has established a $6 billion line of credit to deal with the impact of the strike. But the line of credit "is just prudent in light of some of the messages that we've seen from some of the UAW leadership that they intend to drag this on for months," said GM Chief Financial Officer Paul Jacobson in an interview with CNBC's "Halftime Report" on Wednesday. "We've got to continue to fund the transformation and really position GM for the future for all of our people."

The union on Monday provided a counteroffer to GM's September 21 offer. The details of the union's counteroffer haven't been released.

GM is the sole automaker among the Big Three that has not been spared of UAW's strike expansion on September 22 and September 29.

Before the strike, Ford had set up a line of credit of $4 billion to bolster its financial flexibility in case the union called for a work stoppage.

(With input from Xinhua)