Tesla workers in New York said on Tuesday they will launch a campaign to form a union, setting stage for the latest labor challenge for Chief Executive Elon Musk.

In a letter to Tesla management, the employees announced their plan to unionize with the Workers United Upstate New York.

If formed, the union would be the first for Tesla, which unlike some other US-based automakers has managed to avoid unionization at its US facilities.

Musk has in the past been vocal about his opposition to unions and faced the ire of the US National Labor Relations Board when they directed him to delete a 2018 tweet saying employees would lose their stock options if they formed a union.

“We believe unionizing will give us a voice in our workplace that we feel has been ignored to this point,” the workers said in a press release on Tuesday. “We are only asking for a seat in the car that we helped build.”

The letter to Tesla was first reported by Bloomberg News.

The Buffalo plant does not build cars; it builds solar panels and other products for Tesla’s much smaller energy business. Earlier efforts to organize the company’s auto plant in Fremont, California, have fallen short with the union not even filing to hold a vote by employees.

Buffalo has become a hotbed of labor organizing in recent years. It is home to the first Starbucks store where employees voted in favor of joining a union, Starbucks Workers United. That union and its supporters at the Service Employees International Union are lending support to Tesla’s organizing effort, according to Bloomberg.

The leaders of the union effort have jobs that involve labeling data for Tesla’s Autopilot technology at the company’s plant in Buffalo, New York, according to the report. The union’s logo urges employees to “Take the wheel” and join the union. Some of those leading the organizing effort complain that Tesla is monitoring their keystrokes to track how long employees spend per task and how much of the day they spend actively working, according to Bloomberg.

Musk has praised the work of this group, saying that it is the “Holy Grail” of the company’s self-driving technology.

“We’re getting quite good at auto labeling,” he told investors in April 2021. “The trainers train the training system and then the system auto labels the data and then the human laborers just need to look at the labeling to confirm that it is correct and perhaps make edits.”

Employees said the right to organize a union is a fundamental civil right and the principles it wants the company to agree to would prevent Tesla from threatening or retaliating against workers for organizing a union.

Tesla did not immediately respond to a Reuters request for comment.

– CNN’s Chris Isidore and Vanessa Yurkevich contributed to this report.