While in its third week, dozens of stores across Colorado have joined the grocery workers union strike against Safeway and Albertsons.

About 45 stores and a distribution center have been affected by picket lines since United Food and Commercial Workers Local 7 began its strike 18 days ago.

Stores affected by the strike could have adjusted hours, according to Safeway.

It’s already outlasted the strike against King Soopers in February, when workers across North Colorado and the metro Denver area walked out for 12 days until a temporary peace agreement was established.

While the earlier strike hit Valentine’s Day and Super Bowl Sunday — some of a grocery store’s most lucrative days in a slower month — the strike against Safeway is set to affect the July 4th holiday weekend.

The union has been amping up its strike by adding several stores a day to join the picketing instead of calling all stores at once to join in like it did with King Soopers.

The strike is affecting stores from Denver to Estes Park, Fort Collins, Colorado Springs, Fort Morgan, Pueblo and Grand Junction.

It was spurred after more than nine months of negotiations failed to establish new contracts.

After failing to reach a resolution over issues such as addressing overstaffing and employee benefits, a majority of union workers in parts of the state including the metro Denver area voted to authorize a strike.

In the last update from the union posted on Facebook on June 28, union leaders said it made “significant conceptual progress” on several items but not on important economic issues such as health care and wages.

In a statement, a Safeway spokesperson said the grocer was “committed to engaging in good-faith discussions to reach a new agreement” — adding it hopes an agreement will be made soon.

“We have put forward a strong offer that includes meaningful wage increases, continued investment in secure healthcare coverage, and the long-term stability of the pension plan, reflecting both the dedication of our associates and the real economic conditions facing our industry,” the spokesperson said. “We remain willing to return to the bargaining table and reach a responsible agreement that benefits everyone.”

Safeway has begun hiring a pool of temporary workers to cover shifts of striking workers starting at $22 an hour.

“In the event of a labor strike, confirmed candidates will be extended an offer and hired into this temporary role that will remain active during the strike period only,” according to the job posting.

“To continue supporting our communities during the strike, Safeway in Colorado is hiring temporary workers for a variety of roles, including customer service, stocking, cleaning, and checking,” the spokesperson said.