United Automobile Workers (UAW) called for a nationwide strike against General Motors (GM) along with 48,000 employees amid an impasse in contract talks, the company’s first strike in 12 years.

“We do not take this lightly. This is our last resort,” said Terry Dittes, the UAW vice-president in charge of the GM relationship, said at a press conference on Sunday in Detroit, where the headquarters of the carmaker is located.

Dittes announced that the strike will begin at midnight on Sunday when the GM and UAW’s four-year labour agreement expires, reports Efe news.

The two sides had been negotiating a new four-year agreement and reached an impasse. Since the beginning, the union has been trying to prevent GM from closing two production plants located in the states of Ohio and Michigan. GM has long been criticized by President Donald Trump for moving production to Mexico as well as closing assembly plants in Ohio and Michigan, which could be key states in the elections in 2020.

The company argues that it is necessary to close these plants to respond to changes in the automobile market and says the union is being too demanding with requests to increase wages and guarantee various benefits including medical coverage.

“We presented a strong offer that improves wages, benefits and grows US jobs in substantive ways and it is disappointing that the UAW leadership has chosen to strike at midnight tonight,” the automaker said in a statement on Sunday.

Meanwhile, Dittes said at the press conference that “going into the bargaining season, our members have been very clear of what they will and will not accept in this contract.” He also adds, “We are standing up for fair wages, we are standing up for affordable, quality health care.”

The negotiations have been marked by unprecedented chaos as the union’s president Gary Jones is facing a federal corruption probe for allegedly using union member dues on personal luxuries.

The strike, convened at all GM factories across the country, will be the largest nationwide strike at the business in 12 years. The company’s last major strike was in 2007 when workers stopped work for two days.

(With input from agencies)