The Justice Department has sent a letter to tech billionaire Elon Musk’s super PAC, America PAC, warning that the $1 million daily giveaway in battleground states could violate federal law, a source familiar with the matter said. case.

The letter, previously reported by CNN, came from the department’s Public Integrity Division, the source said. That department handles election-related prosecutions and related matters.

The Justice Department declined to comment and the super PAC’s treasurer did not immediately respond to a voicemail message seeking comment.

Pressure has increased on state and federal authorities to investigate Musk’s lottery as a possible violation of election laws, including a ban on paying people to register to vote. On Monday, a group of ex-prosecutors and other former government officials sent a letter to the Justice Department requesting an investigation.

It is unclear when the letter was sent and what further action the Justice Department might take.

Legal experts have told NBC News that they believe Musk’s fight falls into a legal gray area and could violate election law, but not necessarily.

“I understand what people are saying when they say this is against the law, but I don’t think it is,” said Matthew Sanderson, an election law expert who has worked with Republicans and a consultant to NBC News is.

A source familiar with America PAC’s efforts said Tuesday: “The PAC is confident in the legality of this initiative.”

Federal law prohibits paying people to register to vote. According to the contest website, there are two requirements to enter America PAC’s daily drawing: be a registered voter in one of the seven swing states and sign a petition in support of the First and Second Amendments.

“Our goal is to get 1 million registered voters in swing states to sign the Constitution, specifically the freedom of speech and the right to bear arms,” it says.

Musk also listed a third requirement to win: “be a spokesperson for the petition” in support of the right to speech and gun rights. So far, several winners have appeared in short videos for America PAC talking about their support for former President Donald Trump.

The contest is open to people in Arizona, Georgia, Michigan, Nevada, North Carolina, Pennsylvania and Wisconsin.

Musk, who has supported Trump’s campaign, launched America PAC in an effort to help elect him. Last week, Musk made several appearances in Pennsylvania to encourage last-minute voter registration. During the events, he repeatedly praised Trump and repeated several conspiracy theories.

Musk announced the daily giveaway Saturday at a town hall event in Harrisburg, Pennsylvania, and said he would give away $1 million a day until Election Day. Four winners have been named so far.

Musk, the CEO of Tesla and SpaceX, is the richest person in the world, with a net worth of $240 billion, according to the Bloomberg Billionaires Index.