(CNN) — The United Auto Workers’ national council voted Thursday to recommend its rank and file members ratify a tentative agreement with General Motors.

But the union’s leadership decided that its nearly 50,000 members won’t return to work ahead of the rank-and-file ratification vote on the four-year tentative agreement. That means the strike, which started September 16, could last up to another eight days.

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The union’s negotiating committee recommended the leadership accept the proposed agreement, which would give members pay increases, protected their health insurance coverage without saddling them with the additional payments sought by management, and gives a way for temporary workers at GM to become better-paid permanent employees.

But the deal did not include any shift of vehicles now built in Mexico back to US plants. And it did not save three of the four plants that GM announced plans to close last November – the assembly line in Lordstown, Ohio, as well as transmission plants in Warren, Michigan, and Baltimore. All those plants halted operations earlier this year.

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In a statement, General Motors said, “We encourage the UAW to move as quickly as possible through the ratification process, so we can resume operations and get back to producing vehicles for our customers. Our goal during these negotiations was to ensure that the future of General Motors is one that works for our employees, dealers, suppliers and the communities where we operate. The agreement reflects our commitment to U.S. manufacturing through the creation of new jobs and increased investment.”

Asked what the union got in the contract that made them willing to give up bringing product lines back from Mexico, UAW spokesperson Brian Rothenberg said, “We remain strongly opposed to unallocate the plants and will continue to fight for those jobs in America. They [UAW negotiators] did everything they could to rectify the situation.”

The strike has been the largest at a US business since the last strike at GM in 2007. But that strike was over within three days. This is has been the longest major strike in the auto industry in more than 20 years.

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