About 3,000 cab drivers in the region are represented by the United Steelworkers, who said about 99.5 percent of the 1,800 drivers who work for Frias turned down the contract offer, mostly due to changes in the seniority policy that would change how drivers bid on shifts.
It would also change how they reserve vehicles they drive, the Las Vegas Sun reported Thursday.
Steelworkers Local 711-A representative Julie Holzer said five companies managed by Frias were affected by the contract dispute. She also said it was not expected that other companies join a strike in sympathy.
Union leaders have not yet called for a strike, although turning down the contract gives them permission to do so. Negotiations are continuing.
The previous contract officially ended Sept. 11, but drivers are showing up to work under a contract extension.