Safeway employees at a Denver store walked out Monday, expanding a strike that started this weekend. The strike started small with workers at three stores in Estes Park, Fountain and Pueblo, and a Denver distribution center.

With the clock winding down toward Saturday night's deadline for new contract negotiations, a Colorado union has announced locations where grocery employees are set to walk off the job on Sunday in protest.

Currently, unfair labor practice strikes are limited to Safeway/Albertsons locations in just four cities: stores in Estes Park, Fountain and Pueblo, and a distribution center in Denver.

unlike the February strike by King Soopers workers that started at 77 stores, the Safeway/Albertsons walkout will begin on a more limited scale, first impacting locations in just four Colorado cities.

The union representing Safeway store employees in Colorado has given the required 72-hour notice that the strike is set to begin one minute before midnight on Sunday.