Federal prosecutors have warned Elon Musk that his $1 million-a-day voter petition sweepstakes may be illegal. The pro-Trump Tesla billionaire may have violated vote-buying laws by writing a seven-figure check every day to a randomly selected voter who agrees to sign a petition created by his political action committee, the Justice Department said in a letter. The letter from the Election Crimes Branch of the Justice Department’s Public Integrity Section was sent to Musk’s PAC in recent days, sources told several media outlets. Musk, who is considered the world’s richest person, unveiled the lottery-style giveaway last weekend and has already handed over seven-figure checks to three Trump supporters. Some experts question whether the lottery could violate federal law that bars individuals from paying people to vote a particular way or even to register to vote. The Musk petition expresses support for the First and Second amendments. To sign the petition, a person must be registered to vote in specific swing states, conditions that could be legally fishy. It’s unclear what steps prosecutors might take next if Musk does not halt the giveaway. Musk, who has extensive business dealings with the federal government, says he was once a moderate Democrat. But he has wholeheartedly endorsed Donald Trump in this year’s election and has appeared alongside the former president at several campaign events. Musk has stirred concern by jokingly questioning why no one has attempted to assassinate Vice President Kamala Harris.