Most of the $10 million Kennedy raised from large-dollar donors through Sept. 30 came from voters who did not make any federal donations during either the 2016 or 2020 election cycles.

Of those who did, 2,100 donors — giving nearly $2 million — previously made contributions on the Republican donation service WinRed since 2020. Far fewer donors previously gave through the Democratic tool ActBlue: roughly 1,700 contributors who gave $1.4 million.

Kennedy is running as a self-described “spoiler,” and the draw that the former Democrat has with both the GOP and those who don’t have an obvious political home makes him an unpredictable threat to the establishment of both parties. Some Republicans are already trying to redefine Kennedy as a “typical Democrat,” revealing they’re worried about his appeal to GOP voters.

Both Kennedy and Trump present a fundamental question to voters, said Sen. J.D. Vance (R-Ohio): “Do you think the country has been well-governed by the bipartisan establishment for the past generation?”

“When Kennedy goes out there and runs against that establishment, he has to appreciate it probably ends up splitting votes off from President Trump,” said Vance, who has endorsed Trump’s 2024 campaign.

Federal law requires campaigns to disclose donations only from donors who give at least $200. The POLITICO examination relies on Federal Election Commission data of those large-dollar donors, who make up about two-thirds of Kennedy’s money raised through Sept. 30, the latest campaign finance reporting deadline.

That data shows more than 500 of Kennedy’s biggest donors gave to Trump’s 2020 campaign, more than three times the number of donors who gave to Biden in that race. And in this cycle, more than 160 donors have given to both Trump and Kennedy, while only a handful have given to both Biden and Kennedy.

It’s not just Trump. More than 160 of Kennedy’s donors have also given to biotech entrepreneur Vivek Ramaswamy, who also brands himself as an anti-establishment candidate. Another 100 also contributed to Florida Gov. Ron DeSantis, who has leaned into his anti-vaccine stance on the campaign trail.

“Some members of our party like his positions on vaccines, but other than that he’s a liberal,” said Rep. Byron Donalds (R-Fla.). “That’s not going to work.”

The campaign finance data also suggests Kennedy may be sparking something new in the electorate: More than 60 percent of his large-dollar donors have no donation history on either ActBlue or WinRed, the two parties’ primary donation platforms, since the start of 2020. His coalition — of previously sidelined donors and Republicans, even when he was running in a Democratic primary — may help explain Kennedy’s decision to run as an independent, which he announced on Oct. 9. (The FEC data covers the period through Sept. 30, before Kennedy’s independent bid.)

“No political party or candidate owns votes … Kennedy welcomes everyone into his coalition no matter who they supported in the past,” campaign spokesperson Stefanie Spear said in a statement.

The Trump and Biden campaigns did not respond to a request for comment.

Some Trump allies said they don’t see Kennedy posing a real threat come next November, even if some donors have wandering eyes now.

“Oftentimes people can donate to someone that they’re not even voting for just to see their argument platforms,” said Rep. Matt Gaetz (R-Fla.). “We’ve seen those calls among the sort of junior varsity slate of Republicans seeking the nomination, so I’m not as concerned about [donors].”

Kennedy, a longtime environmental lawyer, is perhaps best known for his work through the nonprofit Children’s Health Defense, which fights against vaccination requirements. While he has sought to not make anti-vaccine activism central to his campaign, he appeared before Congress at the invitation of Republicans this summer to discuss “censorship,” where his skepticism of the Covid-19 vaccine was apparent.

Common occupations among his donors included health care professionals such as physicians, nurses and dentists, as well as practitioners of alternative medicine, such as chiropractors and acupuncturists.

Twenty percent of Kennedy’s newly acquired donors were from California, including several dozen who listed occupations such as “actor” or “producer,” likely reflecting his Hollywood connections.

Few people believe Kennedy’s campaign can come close to winning the presidency, and it faces significant challenges — beginning with the task of getting on the ballot in every state without the backing of a party apparatus.

“Really what you’re talking about is what impact could he have in five or six states that are going to be competitive, [if he’s] on those ballots,” said Sen. Marco Rubio (R-Fla.), who has not yet endorsed in the 2024 race.

“Frankly, I don’t know how many voters out there are willing to spend their vote on a candidate they think has no chance to win,” he said.

In a highly competitive presidential showdown between Biden and Trump, the likely nominees, even small numbers of votes can matter. Political donors are only a small subset of the electorate, but they are among the most highly engaged voters.

“I talk to [Trump] frequently. I think that he is not especially worried about Bobby Kennedy,” Vance said.“I think he’s actually focused on how to persuade voters, which is where he should be.”