United Auto Workers must let its contract with General Motors expire at 23:59.

WXYZ – DETROIT (AP) – The United Auto Workers union leaves its contract with General Motors to expire at 23:59, increasing the risk of strike Sunday night.
Union vice-president Terry Dittes, citing significant differences with the company over wages, health care and other areas, told union officials that the decision to strike would be made on Sunday.
The union says in a letter to GM that union members will show up for regular shifts on Sunday. Both letters were obtained Saturday by the Associated Press. Dittes indicates in his letter to the union officials that they will work until the deadline in order to reach an agreement. But he says that they are also far apart from each other with regard to the use of temporary employees, job security and benefit sharing.