King Soopers filed a complaint accusing the union of delaying negotiations and not bargaining in good faith. Negotiations ended Jan. 17 after the union’s contracts with the company expired and union bargainers decided against presenting King Soopers’ proposal to employees.

More than 10,000 King Soopers grocery workers across the Denver area ended their 12-day strike late Monday after union leaders said they secured some basic protections for returning workers and agreed to resume bargaining with the Kroger-owned chain.