Here’s the clearest 2025-era picture: the biggest megadonors on the Republican side were led by Timothy Mellon, Richard and Elizabeth Uihlein, Sheldon and Miriam Adelson, Elon Musk, and Kenneth Griffin , while the Democratic side was led by George Soros, Michael Bloomberg, Reid Hoffman, and Tom Steyer.

Biggest donors and net worths

[11] [8] [8] [8] [8] [8] [8] [8] [8]
Party Donor Approx. net worth Notable giving
Republican Timothy Mellon Not stated in the source Largest Republican contributor in the 2024 cycle
Republican Richard & Elizabeth Uihlein $12B Among the biggest GOP donors
Republican Sheldon & Miriam Adelson $32.1B One of the top GOP donor families
Republican Elon Musk $342B Top Republican-leaning donor in the list
Republican Kenneth Griffin $42.3B Major GOP donor
Democratic George Soros $7.2B Major Democratic donor
Democratic Michael Bloomberg $105B Largest Democratic donor in the list
Democratic Reid Hoffman $2.4B Major Democratic donor
Democratic Tom Steyer $2B Major Democratic donor

What this means

The richest donors are not always the biggest spenders, because some people with smaller fortunes give a larger share of their wealth. For example, the source notes that Miriam Adelson’s family giving was about $658 million over 2015–2024, which was only around 2 percent of her net worth.

Important caveat

There is no single official “biggest donors to each party in 2025” list, because most reporting tracks the broader election cycle and federal contributions rather than a clean party-only ranking. The best-supported answer from the available reporting is the donor families and billionaires above, especially the top names highlighted in the 2024 cycle coverage that continued shaping 2025 political money discussions.

TL;DR: On the Republican side, the biggest names were Mellon, the Uihleins, the Adelsons, Musk, and Griffin; on the Democratic side, Bloomberg, Soros, Hoffman, and Steyer were the standout donors, with net worths ranging from about $2B to $342B depending on the person.