UPDATE (4:15 p.m.): A spokesperson for Ralphs says if there is a strike the company will initially close all their stores. Says Kendra Doyel, “During a strike, it is difficult to create a good shopping experience for our customers and a good working environment for our employees. We will evaluate the situation as it progresses.”

LOS ANGELES (CBS) — Grocery workers upset with sluggish contract negotiations could strike as early as Sunday night.

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A notice to cancel a contract extension has been filed, putting workers one step closer to a walkout, according to Grocery Workers Union Local 770 President Rick Icaza.

“While we are disappointed the union leadership has taken this step, Ralphs remains committed to reaching an agreement,” Ralphs Vice President of Public Relations Kendra Doyel said. “Active negotiations are ongoing and this does not mean a strike is imminent. Our stores are open for business and we are ready to serve our customers.”

Supermarkets and the union have been battling over health care for 62,000 workers.

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Vons issued the following statement:

We are disappointed by the United Food and Commercial Workers (UFCW) Locals’ decision to give the employers 72 hour notice of the cancellation of the contract extension. Doing so needlessly alarms our employees and our customers. The notice does not mean a strike is imminent or that a strike will necessarily occur at any point. The notice simply allows the union the ability to call a strike if they choose to do so. Vons and the other employers intend to remain focused on the negotiation process and urge the unions to do so the same.

Similarly, Albertsons says it hopes bargaining will continue and that a strike can be averted.

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“We are disappointed that union leadership decided to take this step. We are still in active negotiations and have made progress during our talks this past week and a half. It’s important to remember that the 72-hour notice doesn’t change the terms of the existing contract, and it doesn’t mean a strike is imminent. All it does is give the union the ability to call a strike in the near future. We don’t want a strike, and we hope to continue bargaining rather than continue to alarm our associates and our customers. In the meantime, our stores are open for business and ready to serve the communities in which we operate.”