A wild weekend on the campaign trail underlined two key trends of the 2024 campaign cash race: Kamala's Harris's outsized fundraising prowess and Donald Trump's reliance on an array of friendly billionaires.

Vice President Harris's campaign out-raised Trump by over 3 to 1 in September to cap off a less than three-month sprint as a candidate that saw her raise an unprecedented $1 billion.

Trump's own formal operation has lagged behind. But the former president and his allies have tried to make up the difference with their own flood of billionaire donations directed to outside groups supporting his candidacy.

Some are coming from Tesla (TSLA) CEO Elon Musk, who this past weekend promised daily $1 million giveaways to swing state voters. Last quarter, he donated $75 million to GOP campaign efforts.

But Musk is only the third-most-generous GOP donor at the moment, according to publicly available data.

New filings over the weekend showed that the No. 1 spot belongs to Timothy Mellon. He contributed another $25 million last quarter to a Trump-aligned super PAC named MAGA Inc. That, combined with his $165 million in giving through July, means the heir to the banking fortune of Andrew Mellon has likely spent nearly $200 million this campaign.

Miriam Adelson, the widow of casino magnate Sheldon Adelson, also gave $95 million to her own pro-Trump group in July, August, and September, according to recent filings.

Of course, much of the campaign finance picture won't be known until long after voting has ended — and more will never be known with so-called "dark money" groups also able to accept millions in donations without ever revealing the source.

A focus on Elon Musk

As is often the case, much of the recent focus has been on Musk.

The CEO's high profile was amplified over the weekend when he promised daily $1 million giveaways between now and Election Day open to people who sign an online petition "supporting the US Constitution."

Musk even kicked it off with a novelty check presented to a Trump supporter onstage at a rally this weekend.

The effort includes an offer of "$47 for each registered [swing state] voter you refer that signs this petition," even as a relevant section of federal law bars anyone from paying or accepting money to vote or to register to vote.

Election law experts have told CNN, the Washington Post, and the Associated Press that Musk's maneuver could be illegal.

Pennsylvania Governor Josh Shapiro even suggested an investigation by law enforcement could be warranted in an appearance Sunday on NBC's "Meet the Press," saying the move "raises serious questions that folks may want to take a look at."

A range of other apparent Musk campaign tactics are also under scrutiny.

There is a report that another Musk-funded group, according to the campaign finance watchdogs at OpenSecrets, has set up fake sites that impersonate the Harris campaign and use fake policy positions to create a fictitious "Progress 2028" agenda — seemingly to mislead moderate voters.

In his first campaign appearance, Musk also repeated debunked claims about Dominion voting systems and the 2020 vote. (The electronic voting company was paid $787 million by Fox News in 2023 after the channel made similar claims that were called defamatory).

The company called out "lies" and said it was "monitoring" the situation after Musk's comments.

Musk's get-out-the-vote effort is also under scrutiny, with reports from Reuters and the Guardian suggesting the effort is struggling to meet its goals amid questions raised in those media reports about whether some of Musk's canvassers have lied about the number of voters they reached.

A formal cash race dominated by Kamala Harris

Musk's antics this past weekend coincided with new campaign finance data that confirmed Vice President Harris's effort has raised $1 billion in the quarter that ended on Sept. 30.

It's not just an eye-popping number but is also apparently a record for the biggest fundraising quarter in presidential campaign history.

Her campaign raised over $221.8 million in September to Trump's nearly $63 million, according to the Federal Election Commission (FEC) reports posted late Sunday,

When allied groups are factored in, the Harris operation said it raised $378 million in September alone. That's more than twice the $160 million reported by the Trump operation.

Trump has indeed consistently struggled to raise money, even falling behind the pace of his 2020 run for office.

And in a rare move for a candidate at this stage of the campaign, Trump is even apparently set to take time to raise funds in New York City alongside a rally in Madison Square Garden on Sunday.

Top donors can give nearly $1 million for the "Ultra MAGA Experience," according to an invitation obtained by the New York Times.

Ben Werschkul is Washington correspondent for Yahoo Finance.

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