CHICAGO, Sept. 17 (Xinhua) -- Wearing red T-shirts, hundreds of United Auto Workers (UAW), the largest union in the United States, and their supporters gathered outside General Motors (GM) Co.'s headquarters in downtown Detroit, U.S. state of Michigan Friday afternoon after the union announced late Thursday to begin a strike against all Big Three U.S. automakers.

UAW President Shawn Fain, Michigan Governor Gretchen Whitmer and Vermont Senator Bernie Sanders attended the rally.

In the last 50 years, there has been a massive redistribution of wealth in this country, the Detroit News quoted Sanders as saying in his speech to the crowd, highlighting the rising salaries of the CEOs of the Big Three automakers.

"It is time for you to treat your employees with the respect and dignity they deserve," Sanders said.

While Democratic lawmakers from Michigan issued statements Friday supporting the UAW, Republican lawmakers of Michigan urged automakers and autoworkers to come to an agreement to avoid further economic impact. They also blamed the strike on Democratic policies of accelerating electric vehicle production.

A Republican statement said the government has "signaled that it doesn't care about UAW workers" by passing policies that are "forcing our country into a comply-or-die EV mandate that has already burned billions in American taxpayer dollars."

Another statement said the government's policies have "pushed automakers and autoworkers into a corner ... This strike will have harmful effects on Michigan's economy and families."

In response to the UAW strike, U.S. President Joe Biden urged the Big Three automakers to "go further" in their offers to the UAW.

In a televised speech, Biden noted the massive profits made by automakers in recent years that "have not been shared fairly" with workers.

"The companies have made some significant offers. But I believe it should go further to ensure record corporate profits mean record contracts for the UAW," he said.

Acting labor secretary Julie Su and senior adviser Gene Sperling are heading to Detroit to "offer their full support" to both the union and the automakers.

"The UAW Stand Up Strike begins at all three of the Big Three," the union said in a post on the social media platform X Thursday, covering a GM assembly plant in Missouri, a Stellantis plant in Ohio and a Ford plant in Michigan, and involving a combined 12,700 workers.

The first ever strike of all three at once in the union's 88-year history came after it failed to clinch a deal on a new contract by a deadline on Thursday.

"This is our generation's defining moment," Fain told union members at a Facebook Live event on Thursday night. "The money is there, the cause is righteous, the world is watching."

The union had reportedly been negotiating with all three automakers simultaneously, in a break from previous rounds of contract talks, for significantly higher pay and new benefits.

Particularly, the UAW called for protections for workers with traditional auto jobs as companies increasingly invest in EV production.

In response, GM said in a statement issued Friday that it is ready to return to negotiations and get people to work as quickly as possible, "for the benefit of our team members, customers, suppliers and communities across the United States," NBC News reported.

Carmaker Stellantis NV on Friday gave its latest offer to the UAW, including hiking wages by 19.5 percent, consolidating aftersales parts plants, making salaried workers hourly and increasing the number of supplemental workers the company can use, while not making commitments around future product and investments, the union disclosed. GM and Ford stay with 20-percent wage hike, all below UAW's 36-percent wage hike demand.

Analysts warned that the strike, though limited for the time being, may develop into a prolonged one and a menace to the U.S. economy, as it could cut production by thousands, push up vehicle prices and aggravate supply chain disruptions.