A top auto union official on Sunday (October 6) told striking GM workers that contract negotiations took "a turn for the worse."
48,000 members of the United Auto Workers have been on strike since the middle of September, seeking higher pay, a larger share of General Motors profits, and healthcare benefit protections.
The sides have been meeting daily.
But a letter to the union shared with Reuters, UAW vice president Terry Dittes said "We, in this union, could not be more disappointed with General Motors."
Dittes said the union on Saturday (October 5) put forward a proposal covering wages, signing bonuses and other issues.
GM responded Sunday morning with a counteroffer, which Dittes said "did nothing to advance a whole host of issues."
The carmaker said it was committed to negotiating around the clock to reach a deal.
A statement from GM read "We continue to negotiate in good faith with very good proposals that benefit employees today and build a stronger future of all of us."
Analysts estimate the strike has cost GM over $1 billion dollars.
Workers, too, are paying a heavy price. Strike pay is just a few hundred dollars a week, far less than their wages on the assembly lines.
As the strike stretches into colder weeks ahead, the resolve of both sides will be tested.