King Soopers Union members began voting on whether to authorize a strike. 10,000 workers across the Front Range will be voting from Wednesday until Saturday.

King Soopers and City Market employees in Colorado could strike after their union contract with Kroger expired last week.

About 10,000 workers in Colorado’s Front Range, including 8,000 workers in the Denver metro area, are preparing to vote this week on a potential strike.

Both the president of King Soopers and the union that represents the supermarket chain’s employees believe a strike is likely after union negotiators rejected the company’s contract offer. That’s where the agreement ends.