PARAMOUNT (CBSLA.com) — Employees at the nation’s largest retailer may be walking off the job on one of the biggest shopping days of the year.

Walmart – which is among a handful of local stores opening at midnight on Friday – could see workers at its Paramount store in southeast Los Angeles join a labor action that threatens to disrupt store operations nationwide.

Workers are upset over alleged reductions in hours, scheduling changes and firings affecting an estimated 1.4 million Walmart employees across the U.S.

Walmart does not even officially recognize United Food and Commercial Workers (UFCW), the union behind the planned walkouts, and has filed an unfair labor practice charge with the National Labor Relations Board (NLRB).

But as Bloomberg News consumer reporter Matt Townsend told KNX 1070 NEWSRADIO, it remains unclear exactly how much the protests will affect the retailer’s holiday sales.

“They haven’t really said how many stores they’ll be protesting at or how many people, and they haven’t even been able to say how many actual employees are part of this group,” Townsend said. “There’s a big question mark about how effective it’ll be.”

Despite lingering concerns over the economy, shoppers spent $11.4 billion on Black Friday last year, up almost $1 billion from 2010.