The strike will affect 77 stores in Adams, Arapahoe, Broomfield, Denver, Douglas and Jefferson counties, as well as in Boulder and Louisville.

King Soopers, a chain owned by Kroger, with 121 stores in Colorado and Wyoming, has been negotiating a new contract with the union since October.

This is the second contract in a row that workers at King Soopers have launched a major strike. Three years ago roughly 8,000 workers walked off the job for 10 days with the union raising the demand for a $6 an hour across the board wage increase.