Tesla chief executive Elon Musk challenged US labour union United Auto Workers to organise a vote at the electric car maker's Fremont, California, factory.
The announcement comes as the billionaire entrepreneur criticised President Joe Biden's administration and Democrats for a proposal to give union-made, US-built electric vehicles an additional $4,500 tax incentive. Tesla and foreign car makers do not have unions at their US factories.
In his tweet on Thursday, Mr Musk said the real challenge was the negative unemployment in Bay Area and that not compensating people well would make them leave, as they have many offers.
“I'd like hereby to invite UAW to hold a union vote at their convenience. Tesla will do nothing to stop them,” he said.
Mr Musk has faced the ire of the US National Labour Relations Board, which last year ruled the company had violated labour law. It also ordered Tesla to direct him to delete a 2018 tweet saying employees would lose their stock options if they formed a union.
He tweeted in May of 2018: “Nothing stopping Tesla team at our car plant from voting union. Could do so tomorrow if they wanted. But why pay union dues and give up stock options for nothing? Our safety record is [two times] better than when plant was UAW and everybody already gets health care.”
Tesla subsequently appealed the board's ruling with the New Orleans-based US Court of Appeals. The case is still pending.
The company is also facing several lawsuits alleging racial discrimination and sexual harassment. A California agency last month filed a lawsuit against the company's Fremont plant, accusing it of segregating black employees at the factory.
Tesla has said it does not tolerate discrimination and has taken steps to address complaints by workers.
Mr Musk and his brother, Kimbal, are also under investigation by the US Securities and Exchange Commission over recent stock sells. The Tesla chief executive claims the SEC is “harassing” him with an “unrelenting” investigation because he has spoken against the US government.
Mr Biden has often praised the electric-vehicle efforts made by Detroit car makers General Motors and Ford Motor, including during his State of the Union Speech on Tuesday, even though they sell fewer EVs than Tesla.
The president did not mention Tesla by name in the speech.
“Tesla has created over 50,000 US jobs building electric vehicles & is investing more than double GM and Ford combined,” Mr Musk said in a tweet following the president's address.
Last month, Mr Biden, whom Mr Musk this year compared to a “damp sock puppet”, acknowledged Tesla's leadership role in making EVs after Mr Musk repeatedly complained of being ignored.
Last autumn, Mr Musk said Mr Biden's EV policy appeared to be controlled by labour unions.
Under federal law, at least 30 per cent of workers at a plant or company must sign a petition showing they want to join a union for an election to be held.
Typically, unions like the UAW will not seek an election unless they feel they have the necessary support to win the majority backing necessary.
Agencies contributed to this report