DETROIT (AP) — The United Auto Workers union announced Sunday that its roughly 49,000 workers at General Motors plants in the U.S. would go on strike just before midnight because contentious talks on a new contract had broken down.

About 200 plant-level union leaders voted unanimously in favor of a walkout during a meeting Sunday morning in Detroit. Union leaders said the sides were still far apart on several major issues and they apparently weren’t swayed by a GM offer to make new products at or near two of the four plants it had been planning to close, according to someone briefed on the matter.

“We stood up for General Motors when they needed us most,” union Vice President Terry Dittes said in a statement, referring to union concessions that helped GM survive bankruptcy protection in 2009. “Now we are standing together in unity and solidarity for our members.”

It’s still possible that bargainers could return to the table and hammer out an agreement, but union spokesman Brian Rothenberg said at a news conference that it would be unlikely because it is hard to believe they could resolve so many issues before 11:59 p.m.

GM on Friday offered to build a new all-electric pickup truck at a factory in Detroit that is slated to close next year, according someone who spoke to The Associated Press on the condition of anonymity because that person wasn’t authorized to disclose details of the negotiations, which hadn’t been released to the public. The automaker also offered to open an electric vehicle battery plant in Lordstown, Ohio, where it has a plant that has already stopped making cars. The new factory would be in addition to a proposal to make electric vehicles for a company called Workhorse, the person said.