To announce its new plans to push automakers to make 50 percent of their vehicles fully electric by 2030, the White House held a press conference with executives from Ford, GM, and Stellantis. Notably absent from the event was anyone representing Tesla.

As the biggest American manufacturer of EVs, the snub didn’t go unnoticed by media nor by Tesla’s CEO. Elon Musk took to Twitter to write that it was “odd that Tesla wasn’t invited” to the press conference.

Even Transportation Secretary Pete Buttigieg said he didn’t know why Musk wasn’t invited to the event when speaking to CNBC. But the reasons for the snub may be down to Tesla’s hostility towards unions.

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Responding to questions from reporters about whether or not Tesla’s union stance was behind its missing invitation, White House Press Secretary Jen Psaki indicated that this might be the case. Referring to Ford, GM, and Stellantis, Psaki said: “Well, these are the three largest employers of the United Auto Workers, so I’ll let you draw your own conclusions.”

Just this year, Tesla was forced to rescind illegal policies by the National Labor Relations Board. The boards found that Tesla and Musk repeatedly broke labor laws, taking retaliatory action and coercive interrogations against union supporters.

The Biden administration’s pro-union attitude, meanwhile, was made clear in a previous statement in which it said one of the benefits of promoting EVs was creating “good-paying, union jobs.”

Although Tesla is the only American manufacturer without UAW-represented workers, foreign automakers with local plants are not represented either and they, too, weren’t invited to the event. That could help further explain why the White House chose not to extend Tesla an invitation.