Safeway workers in several Colorado cities entered the third day of labor strikes Tuesday against Safeway and Albertsons over alleged unfair labor practices, with picketing in Grand Junction prompting a temporary store closure.

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.

Safeway workers in Colorado Springs will join strikes happening around the state, according to the UFCW Local 7 union.

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.