Tesla employees in New York have launched a campaign to organize a union with Workers United Upstate New York, according to a release posted to Twitter Tuesday.

The union, Tesla Workers United, would be the first for Tesla if it is formed. The campaign will set the stage for a new labor battle with CEO Elon Musk, who has openly expressed his opposition to unions in the past.

“We want Tesla to be the company we know it can be,” the workers wrote in the release. “Our union will further Tesla’s principles and objectives, including by helping to serve as the conscience of the organization and by ensuring and deepening our culture of trust and respect.”

In 2018, Musk shared a tweet that said employees would lose stock options if they formed a union. “Nothing stopping Tesla team at our car plant from voting union,” he said at the time. “Could do so tmrw if they wanted. But why pay union dues & give up stock options for nothing?”

He was later directed to delete the tweet by the U.S. National Labor Relations Board.

The next step for organizers is to collect signatures from employees saying they want a union. Then, they’ll likely file a petition with the National Labor Relations Board, indicating they seek to hold a union election.

At least 30% of the employees in a potential bargaining unit must sign cards for an election to be held.

Tesla and Musk did not immediately respond to requests for comment.

–CNBC’s Annie Palmer and Lora Kolodny contributed to this report