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.

About 45,000 grocery workers have authorized a strike at Ralphs, Albertsons, Vons and Pavilions stores in Southern California to protest unfair labor practices.

Workers at Albertsons, Pavilions, Ralphs and Vons grocery stores will begin preparations on Thursday for a possible strike.

Union members of the United Food and Commercial Workers (UFCW) in Southern California and the Pacific Northwest have voted this week to authorize a worker strike against Kroger and Albertsons stores, Supermarket News reported.

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.