The United Auto Workers’ strike against General Motors could continue for the foreseeable future, as the union on Sunday said talks between the sides have “taken a turn for the worse.”

UAW Vice President Terry Dittes, in a letter to members on Sunday, said the union plans to continue to negotiate but a Sunday morning proposal from GM was inadequate and “reverted back to their last rejected proposal and made little change.” The offer, he said, was a counter proposal from an “extensive package” the union provided to the automaker on Saturday night.

“The Company’s response did nothing to advance a whole host of issues that are important to you and your families!” Dittes wrote. “It did nothing to provide job security during the term of the Agreement.”

GM, in response to the letter, said the company continues “to negotiate in good faith with very good proposals that benefit employees today and builds a stronger future for all of us. We are committed to continuing discussions around the clock to reach a resolution.”

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