Union workers at Fry's Food Stores and Safeway supermarkets in Arizona are to vote next week on whether to strike if leaders of the union and companies fail to agree on terms of a new labor contract.

Strike-authorization votes are to be held Monday evening and Tuesday morning in Phoenix, and Tuesday evening and Wednesday morning in Tucson, confirmed Paul Rubin, secretary-treasurer of the United Food and Commercial Workers Union Local 99.

He said the union represents about 20,000 employees of the two grocery chains, including 3,000 to 3,500 in Tucson. Current contract extensions run out Oct. 3.

An authorization vote does not mean there will be a strike. A positive vote authorizes labor leaders to call a strike later if they don't reach agreement or extend negotiations.

Rubin said talks are to resume Thursday and that union leaders hope they can arrive at a new contract without a strike.

Cathy Kloos, Safeway director of public affairs and government relations, said the grocer's goal is to reach a "fair and competitive" negotiated settlement.

"Our negotiations with Local 99 have been progressing slower than we had hoped. But progress is being made, and these negotiations hopefully will result in new contracts without a strike or other work disruptions," Kloos said.

More than 9,100 Arizona Safeway employees are represented by the union.

"No one benefits from a strike, especially in these economic times with jobs scarce and unemployment at its highest rate in 26 years," Kloos said.

Fry's spokeswoman JoEllen Lynn also stressed that negotiations are continuing.

"We hope to reach an agreement in the near future that is fair to everyone," Lynn said.

Fry's has 2,766 associates working in Tucson, but she did not say how many are represented by Local 99.

Representatives of the union and grocers were reluctant to disclose specific contract issues. In the past, negotiations have bogged down over who bears health-care costs and over proposed cuts in pay.