The union representing 62,000 grocery workers in southern California has received the go-ahead from members to call a strike if an acceptable contract deal cannot be reached with Ralphs, Vons and Albertsons supermarkets, officials said on Sunday.

Over 90 percent of workers voted on Friday and Saturday to authorize a strike, far in excess of the two-thirds vote required, said the United Food and Commercial Workers union.

Mickey Kasparian, the president of UFCW Local 135, said a federal mediator would continue to work toward a resolution, but a strike could be called in five or six days if there are no positive developments.

If we don't get a deal, we'll take this fight to the streets, Kasparian said.

In 2003, the region played host to the longest work stoppage in the history of the U.S. grocery industry. That bitter, four-and-a-half-month standoff shifted more than $1 billion in sales, and the loyalty of some shoppers, to competitors.

In the latest discord, southern California grocery store employees have been without a contract since it expired in March. While the union workers previously voted to authorize a strike, changes to offers being negotiated made another vote necessary.

Ralphs owner Kroger Co, Vons owner Safeway Inc and Albertsons owner Supervalu are negotiating as a group.

Kendra Doyel, a spokeswoman for the grocery chains, said the strike authorization vote is a common negotiating tactic and does not necessarily mean the union will call a strike.

Ralphs, Vons and Albertsons remain committed to reaching a contract that is good for our employees and keeps these union jobs sustainable for the future, Doyel said in a statement.

Grocery employees are members of seven union locals. The biggest is United Food and Commercial Workers Local 770.

The main point of contention in talks is healthcare coverage. The union wants the supermarkets to contribute more to a health fund it claims will run out of money within a year.

Southern California, a supermarket union stronghold, is one of the most competitive grocery markets in the United States.