United Auto Workers
United Auto Workers (UAW) President Shawn Fain, right, shown here at the celebration of a win Tennessee last month, hopes for a successful outcome at an election in Alabama AFP

The US auto workers union's drive to organize auto plants in the southern United States faces a second test this week at Mercedes-Benz in Alabama following a triumph last month.

Some 5,200 workers at the Mercedes auto manufacturing plant and battery complex near Tuscaloosa, Alabama will decide whether to join the United Auto Workers in a federally-administered election that runs from Monday through Friday.

The election comes on the heels of the UAW's win on April 19 at Volkswagen's Chattanooga, Tennessee plant in the first successful UAW drive at a foreign-owned auto plant in a southern state.

The UAW has faced greater opposition at Mercedes-Benz US International (MBUSI) compared with VW, which maintained a neutral posture towards the election in official communications.

Workers who back the union have filed complaints with the National Labor Relations Board alleging the company unfairly retaliated against workers over union activity, surveilled workers and other charges, said the NLRB, which is overseeing the election.

The UAW has also filed a complaint under a new German law on global supply chain practices, charging the company with a "clear human rights violation" over allegedly firing one pro-union worker with cancer and forcing employees to attend meetings in which plant leaders railed against the union.

MBUSI "fully respects our Team Members' choice whether to unionize," a company spokeswoman said.

"MBUSI has a strong record of success over the past 25+ years operating as One Team in Alabama," she said. "We believe open and direct communication with our Team Members is the best path forward to ensure continued success."

The historic VW vote came on the heels of the UAW's strike last fall on Detroit automakers General Motors, Ford and Stellantis that resulted in large wage hikes and lifted the profile of UAW President Shawn Fain, who enlisted President Joe Biden to appear with autoworkers on the picket line.

"If they win, it is yet another momentum builder" for the UAW, said Art Wheaton, director of Labor Studies at Cornell's School of Industrial Relations.

A win would bolster campaigns of workers at other factories in the South at Honda, Toyota, Hyundai and other automakers, said Wheaton.

Wheaton noted that even a defeat in Alabama could pave the way for eventual success, noting that the UAW's in Tennessee failed in two prior elections at VW before winning this time.

A defeat will provide a "benchmark," said Wheaton, adding that the union "is in it for the long haul."