Several news outlets are saying that the Ralphs grocery store chain could close as soon as Sunday night if it fails to come to an agreement with the grocery worker's union. 

According to Business Week:

Ralphs spokeswoman Kendra Doyel said her company remained committed to reaching an agreement, but if there was a strike, the company won't ask customers to cross a picket line to shop.

"If there is a strike, Ralphs will initially close all of our stores," said Doyel in a statement. "During a strike, it is difficult to create a good shopping experience for our Customers and a good working environment for our Employees."

Vons and Albertsons will also be affected by a strike, but have said they will remain open.

At issue is an agreement about health care contributions: the grocery stores have been unwilling to change the current agreement, where grocery workers make a contribution toward coverage.  The union, which has been negotiating with the grocery stores for the past eight months, canceled a contract extension Thursday, leaving the possibility of a strike after 72 hours had passed.

In August, the 62,000 union members authorized a strike if an agreement can't be reached.

The groceries stores and union last came to blows in 2003, which resulted in a several month lockout.