What has already been dubbed a major strike against the top three Detroit car manufacturers, Ford, General Motors (GM), and Chrysler producer Stellantis, saw the joining of another 7,000 members earlier on Friday marking the strike the biggest US United Auto Workers' (UAW) strike.

Shawn Fain, the United Auto Workers' president, called on workers at Ford and GM plants located in Chicago and Michigan to take part in the US' first joint strike against automakers in Detroit.

Fain said in a live-streamed YouTube message "I'm calling on Ford's Chicago assembly plant to stand up and go on strike, and I'm calling on GM's Lansing Delta Township to stand up and go out on strike," adding that "Our courageous members at these two plants are the next wave of reinforcements in our fight for record contracts."

The UAW is seeking 40% wage hikes that would match the average increases by CEOs over the last four years.

Other key demands include the elimination of different worker pay and benefit "tiers", a cost-of-living adjustment, and the re-establishment of retiree medical benefits and a pension for junior employees.

The one-week-old strike has so far had a limited effect on company profits while introducing new pressures on auto parts suppliers to the Big Three.

Biden's UAW involvement sparks GOP critique

During the second round of presidential debates, Republican candidates strongly criticized US President Joe Biden for his involvement in the United Auto Workers' (UAW) strike on Tuesday and attributed the actual cause of the strike to his administration's economic policies.

"Joe Biden should not be on the picket line. He should be on the southern border working to close our southern border because it is unsafe, wide open, and insecure," senator from South Carolina Tim Scott said during the debate on Wednesday night.

In response to the ongoing strike, American entrepreneur Vivek Ramaswamy urged the demonstrators to gather in Washington D.C. and arrange a picket right in front of the White House, emphasizing that this is the most appropriate location for their protests.

Read more: Kia, Hyundai recall millions of cars in US over engine fire hazards

"Why are those workers actually there? It's because of all of the spending that Biden has pushed through in the economy that's raised the inflation," former United Nations ambassador and South Carolina governor Nikki Haley said.

According to North Dakota Governor Doug Burgum, the primary cause of the strike is Biden's involvement in capital markets.

Meanwhile, Florida governor Ron DeSantis said: "People in Washington are shutting down the American dream with reckless behavior. They borrowed, they printed, they spent, and now you're paying more for everything,"

On his account, Former US President Donald Trump criticized President Joe Biden for his participation in the United Auto Workers' (UAW) strike, alleging that Biden's entire professional history has involved actively undermining the economy and unions.

Read more: US auto workers union extends strike at GM, Stellantis