Workers at two Mercedes-Benz factories near Tuscaloosa, Ala., voted on Friday against allowing the United Automobile Workers to represent them, a stunning blow to the union’s campaign to gain ground in the South, where it has traditionally been weak.
The defeat came after Kay Ivey, Alabama’s governor, and other Republican leaders argued that a pro-union vote would choke off the investment that has transformed the state into a major auto producer. The union’s setback dims the chances that it will be able to quickly organize workers at Hyundai and Honda, which also have large factories in Alabama.
The vote had national significance as a test of whether the U.A.W. could build on a string of recent victories and make strides in a state whose elected officials have been hostile to organized labor. The union has said it wants to organize every automobile factory in the United States, expanding its membership to include the employees of companies like Toyota and Tesla.
But the loss at the Mercedes plants will almost surely slow down the union’s campaign and probably force it to do more spadework to secure the support of workers before seeking to hold elections at other auto plants. Union leaders will want to spend time figuring out how best to counter the messages and tactics of local lawmakers and company executives.
“This loss stings,” Shawn Fain, the president of the U.A.W., said at the storefront headquarters of the union’s local branch down the road from the Mercedes factories in Vance and Woodstock, Ala.
But “most of us lost elections in our lives,” he added. “We learn from it. We move forward, and that’s what we intend to do.”
Mercedes workers voted 56 percent to 44 percent against joining the union, according to the National Labor Relations Board, which oversaw the election. Close to 4,700 ballots were cast, representing a large majority of the 5,075 employees who were eligible to vote.
Auto executives and conservative lawmakers are likely to closely study the vote at Mercedes to figure out the best approaches to fend off the U.A.W. and other unions in future contests and to deter union campaigns from the get-go.
“The workers in Vance have spoken, and they have spoken clearly!” Ms. Ivey said in a statement. “Alabama is not Michigan, and we are not the sweet home to the U.A.W.”
The South has become an important battleground. States like Georgia, South Carolina and Tennessee are attracting much of the billions of dollars that automakers and suppliers are investing in electric vehicle and battery factories. The U.A.W. wants to represent workers at those factories.
Mercedes produces sport utility vehicles in Vance and battery packs for electric vehicles in Woodstock. Polling had been underway all week at the two factories.
“We thank all team members who asked questions, engaged in discussions and, ultimately, made their voices heard on this important issue,” the company said in a statement on Friday.
In a campaign conducted largely by word of mouth, union activists argued that in addition to better pay and benefits, the U.A.W. would protect Mercedes workers from abrupt changes in their schedules and long shifts, including on weekends.
“If it wasn’t for us building those cars, you wouldn’t be putting the money that you’re putting in your pockets,” said Kay Finklea, who works in quality control at Mercedes and campaigned for the union. “So treat us with dignity, treat us with respect and pay us.”
But activists acknowledged that many workers who were unhappy with working conditions at Mercedes were also reluctant to join the union, swayed by warnings from company executives and politicians that membership would lead to onerous dues and loss of control over their jobs.
Mercedes tried hard to block the union. Last month, in an apparent attempt to address employee complaints, the company shook up local management, appointing Federico Kochlowski as chief executive of the German company’s U.S. unit.
Mr. Kochlowski, who has worked at Mercedes for about 20 years in various manufacturing positions in China, Mexico and the United States, acknowledged that there were problems at the Alabama plants and promised to make improvements.
“I understand that many things are not OK,” he said in a video posted by Mercedes online. “Give me a shot.”
Bart Moore, who works in material handling at Mercedes delivering parts to the assembly line, said he was hopeful that Mr. Kochlowski would follow through on his promises. “We’ll see what he comes through with,” Mr. Moore said. “You never know.”
The U.A.W. has filed six charges of unfair labor practices against Mercedes with the labor relations board, saying the company disciplined employees for discussing unionization at work, prevented organizers from distributing union materials, conducted surveillance of workers and fired workers who supported the union.
“This company, like most others, operated off the same playbook of fear, threats, intimidation,” Mr. Fain said Friday.
Mercedes denies the claims.
Past attempts by the U.A.W. to represent workers at Mercedes and other automakers in the South had failed. But the U.A.W. is stronger than it has been in years after winning a unionization vote last month at a Volkswagen plant in Tennessee where it previously lost two elections. The union also won hefty pay raises last year for workers at Ford Motor, General Motors and Stellantis, the parent company of Chrysler, Jeep and Ram.
Mercedes’s campaign against the union “had way more effect than we anticipated,” said Robert Lett, who works in the Woodstock battery factory and campaigned for the union. But he said the union would try again.
“It doesn’t change our resolve,” Mr. Lett said of the loss. “The fire is there for a change.”