WASHINGTON — The Justice Department warned Elon Musk’s America PAC in recent days that his $1 million sweepstakes to registered voters in swing states may violate federal law, people briefed on the matter told CNN.

Musk, who has thrown his support behind former President Donald Trump and is spending millions of dollars supporting his candidacy, has publicized the $1 million prize by his political action committee aiming to increase voter registrations in hotly contested states.

Even bullish Tesla investors are starting to get nervous about Elon Musk’s rhetoric online and his “dark MAGA” turn, which could lead to some awkward moments on Wednesday’s earnings call.

Musk’s initial promise to pay prizes to registered voters immediately raised concerns from election law experts and some state officials who questioned whether it ran afoul of the law.

Federal law bars paying people to register to vote. The language of the petition currently promises $1 million prizes to people chosen at random for signing a petition in support of First and Second Amendment freedoms. But to sign the petition, you must be registered to vote in specific states.

A letter from the Justice Department’s public integrity section, which investigates potential election-related law violations, went to Musk’s political action committee, according to people briefed on the matter.

CNN has reached out seeking comment from Musk, several email addresses listed on the super PAC’s website, the group’s treasurer, and Musk’s press team at the X platform.

The Justice Department declined to comment.

“We want to try to get over a million, maybe 2 million voters in the battleground states to sign the petition in support of the First and Second Amendment,” Musk said in announcing the sweepstakes at a Trump campaign event in Harrisburg, Pennsylvania, on Saturday. “We are going to be awarding $1 million randomly to people who have signed the petition, every day, from now until the election.”

After Pennsylvania Gov. Josh Shapiro, a Democrat and former state attorney general, said Sunday that the giveaway was “deeply concerning” and deserved legal scrutiny, Musk posted on his X platform that it was “concerning that he would say such a thing.”

In response to a post claiming Musk was “paying to register Republicans,” Musk said winners “can be from any or no political party and you don’t even have to vote.” He did not address the potential legal problem of only opening the lottery to registered voters.

On Sunday, the second day of the sweepstakes, the super PAC reframed its messaging around the giveaway, describing the money as payment for a job. In social media posts, the group said winners would be “selected to earn $1M as a spokesperson for America PAC” – and subsequently posted pro-Trump testimonial videos featuring the winners.

However, several election law experts who spoke to CNN pointed out that the fine print on Musk’s super PAC website explaining the official terms of entry did not change. Only petition signers can win the $1 million prize, and signers “must be registered voters of Arizona, Michigan, Georgia, Nevada, North Carolina, Pennsylvania, or Wisconsin.”

It’s not clear when Musk received the Justice Department’s letter and whether it prompted changes to messaging around the giveaway. — CNN