New York CNN Business  — 

Tesla CEO Elon Musk, a vocal critic of unions and the United Auto Workers’ efforts to organize his employees, is inviting the union to hold an organizing vote at the company.

On Twitter late Wednesday night, Musk said that Tesla is able to hire and retain workers only in the current, very tight labor market by paying and treating them well, and he is not concerned about having a union vote at the company.

“I’d like hereby to invite UAW to hold a union vote at their convenience. Tesla will do nothing to stop them,” he said in the tweet.

Musk was responding to a Twitter chain that started with President Joe Biden praising two unionized automakers — General Motors and Ford (F) — for their investments in building electric vehicles. Biden, perhaps the most pro-union president in history, has repeatedly praised the EV efforts of unionized automakers, such as GM (GM), Ford (F) and Stellantis, while conspicuously ignoring Tesla, which to date has invested far more in EV development and built far more of those vehicles in the United States.

When rock legend Gene Simmons responded to Biden’s tweet suggesting that the President didn’t mention Tesla because it is non-union and headquartered in Texas, a “right to work” state, Musk responded to point out that the company has not closed its California plant and is actually considering expanding it. He then made the offer for the union to hold a vote.

Musk followed up later by tweeting that Tesla factory workers’ compensation is the highest in the auto industry. Most Tesla workers receive stock options, which can be very lucrative considering the performance of the stock in recent years.

Musk has threatened that workers could lose that benefit if they vote for a union, a stance that was a California labor judge ruled to be an illegal action against employees’ rights to freely choose whether or not to organize. Stock options workers already accumulated could not be revoked if they later voted to unionize.

Worldwide workforce

A company filing showed that Tesla had nearly 100,000 employees worldwide at the end of last year, but it did not show the split between its plants in California, Texas, Nevada, Western New York, Shanghai and a new plant about to open outside of Berlin.

The UAW did not have an immediate comment on Musk’s offer to hold a vote. It has been trying to organize the California plant virtually since it started production a decade ago.

The UAW and the National Labor Relations Board, the government agency that oversees unionization votes, have repeatedly cited Tesla and Musk for illegal or improper anti-union activities, including allegations that the company fired employees who supported and promoted the union.

Typically a union vote is held when at least one-third of employees at a company or specific workplace sign cards asking to be represented. And unions typically don’t file the cards to request an election unless they have significantly more support than that, most often from a large majority of workers.

In some instances a company will agree to recognize a union without a vote, typically as part of an agreement with a union that already represents its employees at other facilities. An employer can also agree to hold a vote without the union filing cards, but it is not clear if that is what Musk has done in this case, since offering an election on Twitter is not a formal filing with the NLRB.

When organizing votes are held, employers almost always lobby workers to vote no, arguing they would be worse off under union leadership. Even when employers stay neutral, as was the case at a UAW vote at a Volkswagen plant in Chattanooga, Tennessee eight years ago, outside groups opposed to unions can lobby workers to vote no and defeat the organizing effort.

It’s also not clear if Musk is offering to stay neutral if a vote is actually scheduled, and whether such a vote would be only at the Tesla plants in relatively pro-union California or Nevada, or whether it would include employees at the newly-opened facility outside of Austin, Texas.

Big boost for union efforts

Organizing a high-profile company such as Tesla would be one of the US labor movements’ greatest victories in decades, said Alexander Colvin, professor at the Cornell University school of industrial and labor relations.

“It would be a crucial success,” Colvin said. “It’d be up there with successful organizing Amazon (AMZN).”

Union membership nationwide has dropped to only 10.3% of all workers, and only 6% of private sector employees, down from 16.8% in 1983 when the Labor Department started tracking the data. Organizing campaigns are crucial to unions regaining some of their lost power.

But unions recently have been more likely to lose high-profile votes, such as a recent one at an Amazon warehouse in Alabama. That election is being rerun right now after a finding of improper activity by management during the course of the initial vote.

A small, independent union, Starbucks Workers United, is having some success organizing individual stores in the coffee chain, so far winning votes at two locations in Buffalo and one in Mesa, Arizona. But that’s only three of 9,000 US stores owned by Starbucks.