WILLIAM BRANGHAM: The 2024 campaign was already shaping up to be the most expensive election of all time.

But now several high-profile billionaires are dumping massive amounts of money into the presidential race.

Laura Barron-Lopez has the details of who these donors are and what their impact might be.

LAURA BARRON-LOPEZ: Thanks, William.

New reporting shows two notable donations.

Businessman Timothy Mellon gave $50 million to a Donald Trump-aligned super PAC the day after the former president was convicted of 34 felonies.

And former New York City Mayor Mike Bloomberg, who challenged Joe Biden for the Democratic nomination in 2020, is spending $20 million to help the president's reelection effort.

The campaigns themselves are reporting huge fund-raising hauls as well.

In May, the Biden team raised $85 million, but was outshadowed by the Trump team, which reported raising $141 million.

Let's explore where the money is coming from and where it's being spent with Anna Massoglia, editorial and investigations manager at OpenSecrets.

Anna, thanks so much for being here.

ANNA MASSOGLIA, Editorial and Investigations Manager, OpenSecrets: Thank you so much for having me.

LAURA BARRON-LOPEZ: The contributions from megadonors like Mike Bloomberg and Timothy Mellon are eye-popping.

How unusual are these donations and what do you think it'll do for the campaigns?

ANNA MASSOGLIA: Well, multimillion-dollar donations to super PACs are becoming run-of-the-mill at this point.

But the size of these donations and the sources, in particular in the case of Mellon, where we have not seen a donation this large coming from him, and it being such a huge donation compared to others, it's one of the largest donations that we have seen, really stick out.

With Mike Bloomberg, he has a long history of giving, of funding his own presidential campaign, so it is to be expected that he would give money to Joe Biden or to a super PAC supporting him.

But when it comes to Timothy Mellon, his influence is much newer, and we are just now starting to really see what the full capacity of that influence is.

LAURA BARRON-LOPEZ: Yes, as you said, a lot of people know who Mike Bloomberg is.

They don't really know who Timothy Mellon is.

Who is he, and how much of a big deal do you think it is that he's contributing to Trump at this point?

ANNA MASSOGLIA: It's significant.

Mellon is also given to a super PAC supporting Kennedy, as well as now to Trump, which really plays into the complicated dynamics of the Kennedy campaign's influence on the two main candidates.

LAURA BARRON-LOPEZ: To RFK Jr. ANNA MASSOGLIA: Yes, that's correct.

And one of the things that's noteworthy is, also, this is not money going directly to the Trump campaign.

This is going to a super PAC supporting him, MAGA Inc., which is the main super PAC aligned with the Trump campaign run by Trump allies.

One of the big differences there is that super PACs can raise and spend unlimited sums, unlike campaigns which are limited with how much they're able to bring in from one specific individual.

And the super PAC really opens the door for more billionaires to be able to pour money in to influence the elections.

LAURA BARRON-LOPEZ: So we know how much these billionaires are spending because it had to be disclosed, but what about the impact of money with murkier origins, so-called dark money?

How prevalent is that this year?

ANNA MASSOGLIA: Dark money is pouring into U.S. elections.

One of the new ways that we are tracking at OpenSecrets is dark money contributions to super PACs.

While super PACs, as I mentioned, have to disclose the origin of their funding who's donating to them, they can just disclose dark money groups, 501(c) groups that are not technically political committees, so they don't have to disclose the ultimate source of funding.

They may disclose shell companies.

And so even though the super PAC is following the letter of the law by disclosing who is giving the money to them, they are able to skirt the disclosure requirement because the ultimate funder is not known.

And that is something that we're seeing on track for a new record this cycle with money pouring into super PACs from dark money groups.

LAURA BARRON-LOPEZ: President Biden had a big cash week this week.

He brought in $30 million at a Hollywood fund-raiser.

That was the single biggest cash haul at a single event for the Democratic Party, broke a record there.

But we're seeing that President Biden's cash advantage is slipping away and that Donald Trump is starting to catch up.

What -- how significant is that?

Is it going to have a long-term impact?

ANNA MASSOGLIA: We're certainly seeing the tables turn where, for several months, Biden was outraising Trump, had a larger cash reserve.

And just these last two months, we're really starting to see Trump catching up and this month actually exceeding what Biden had raised, and especially Trump and the RNC compared to Biden and the DNC, which is another important dynamic, not just for the campaigns, but also for the parties, since that influences a number of other candidacies.

And the money that's flowing in now, it depends how it's used.

A big expense that Donald Trump has that Joe Biden does not would be legal fees.

And so much of his money is being burned through for legal fees, whereas Biden is able to devote so much more funding to things like media and outreach and staffing, expenses that Trump still has, but has less funding overall for when you count the legal fees.

LAURA BARRON-LOPEZ: How much money is going into the organizations like Heritage Foundation that is establishing Project 2025, which is this blueprint for a second Trump term?

ANNA MASSOGLIA: One of the issues with outside groups such as 501(c) nonprofits is that they aren't expressly political, so they aren't legally required to disclose their fund-raising to the Federal Election Commission, who their donors are, or even details of their spending, as long as they aren't expressly advocating for a candidate.

And so with the case of The Heritage Foundation and Heritage Action, it's a 501(c)(3) and a (c)(4), so they - - we won't know anything about their finances that's substantial for this year until their next tax return is due.

And, even then, we won't know who's funding these efforts, and very few details about how their spending is.

LAURA BARRON-LOPEZ: Anna Massoglia of OpenSecrets, thank you for your reporting.

ANNA MASSOGLIA: Thank you for having me.