Elon Musk gave about $44 million to his pro-Donald Trump spending group during the first half of October, federal disclosures showed on Thursday, as the billionaire stepped up his efforts for the Republican candidate in the November 5 election.

The contributions, disclosed in a filing to the Federal Election Commission by Musk's America PAC group, come after a prior report showed he gave the group about $75 million over three months between July and September.

America PAC, which is focused on turning out voters in closely contested states that could decide the election, also disclosed spending more than $47 million in the first half of October.

The Trump campaign is broadly reliant on outside groups for canvassing voters, meaning the super PAC founded by Musk — the world's richest person — plays an outsized role in what is expected to be a razor-thin election between Trump and Vice President Kamala Harris.

Separately, Trump's campaign reported spending more than $88 million on ads in the first half of the month, leaving him with $36 million in the bank for the final stretch of campaigning, according to a separate filing to the Federal Election Commission.

Trump's campaign raised $16 million during the period.

The Harris campaign, which has outraised and outspent Trump's campaign in recent months, reported spending more than $130 million on ads in early October. Harris' campaign raised $97 million during the first half of the month and had $119 million in the bank on October 16, according to its disclosure.

Another conservative super PAC, the Sentinel Action Fund, also reported receiving $2.3 million from Musk.

Musk's donations to America PAC propel him into the exclusive club of Republican mega donors, a list that also includes banking heir Timothy Mellon and casino billionaire Miriam Adelson.

As part of its plan to stir support for Trump, America PAC has been giving away $1 million per day to a randomly selected signatory of its online petition, which is only open to registered voters in battleground states.

The Justice Department sent a letter to America PAC warning that the giveaways may violate federal law, CNN reported on Wednesday.

The petition falls into a gray area of election law, and legal experts are divided about whether Musk could be running afoul of prohibitions on paying people to register to vote.

Musk named two winners, one in Michigan and one in Wisconsin, in posts on social media platform X late Thursday following the DOJ warning. America PAC has not responded to requests for comment about the letter.