Operations at an auto giant's facilities across the United States are seen to be crippled as around 49,000 employees said they will go on strike to protest the company's unfair labor practices, a union representative told Reuters.

The United Auto Workers Union announced its personnel at General Motors Company manufacturing plants in the US will stage a walkout on Sunday night as labor contract deals with the Detroit-based carmaker had fallen apart. Some 200 leaders of UAW voted in favor of a strike after a meeting in Detroit.

In a collective voice of frustration, the union leaders said that they have stood up for the car company during times when they needed them the most. "Now, we are standing together in solidarity for our members," UAW Vice President Terry Dittes disclosed in a statement. The union announcement was made moments after it let its labor contract with GM expire, late Saturday.

According to sources, both parties could still not agree on several key matters on wages, job permanency, contractual employment, health care, and profit-sharing and they were not persuaded by the company's offer to manufacture new units in any of the facilities General Motors had been planning to shut down.

A union-led strike would greatly hamper General Motor's overall output and potentially prevent the car giant from assembling automobiles in Mexico and Canada. This would translate to fewer cars for clients to select from on dealership stores.

UAW chose General Motors, which earns more income compared to both Fiat Chrysler and Ford, as its target company. This means it's the union's focus of labor bargaining and would be the first US carmaker to be dealing with a strike. As this developed, schedules for picket lines have already been set up near the gates to one UAW office in Detroit.

The walkout would be UAW's first show of opposition since a 2-day operations stoppage at the company in 2007. Union leaders extended contracts with Fiat Chrysler and Ford for the time being, but the agreement with GM was still set to be scrapped Saturday night.

Discussions between General Motors and UAW were strained right from the beginning, all because the company seeks to shut down four of its assembly lines in the US, including facilities in Ohio and Michigan. UAW has vowed to stop the closures.

One of the major issues is that General Motors is earning huge profits - $8 billion in 2018 alone - and UAW workers want a bigger share. The union also wants yearly pay increases to guard protect them against an "economic downturn," but GM wants to pay a lump sum instead of as American car companies want to steer away from higher fixed costs.