Billionaire Citadel founder Ken Griffin has invested about $40 million so far this year to help Republicans defend their House and Senate majorities in the 2026 midterm elections.
The Wall Street Journal reported that a large portion of Griffin’s donations are directed toward key Senate contests.
People familiar with Griffin's giving told the Journal that the total could easily double before Election Day.
His largest contribution was a $10 million donation to the Senate Leadership Fund, a super PAC aligned with Senate Majority Leader John Thune, R-S.D.
Griffin also contributed $6.5 million to groups supporting individual Republican candidates, including Sen. Dan Sullivan of Alaska, Rep. Ashley Hinson of Iowa, and Sen. Susan Collins of Maine. Sullivan and Collins each received backing through $2.5 million donations, while the group supporting Hinson received $1.5 million.
The Cook Political Report rates the Alaska and Maine Senate races as tossups, while Iowa is considered to lean Republican.
According to the Journal, Griffin does not plan to support Texas Republican Senate nominee Ken Paxton. The Cook Political Report rates that race as leaning Republican.
Griffin, whose net worth is estimated at more than $50 billion, ranked as the nation's fifth-largest political donor during the 2024 election cycle, according to OpenSecrets.
People familiar with his political giving said Griffin is concentrating on Senate races because he believes senators' six-year terms can have a greater long-term impact on the Republican Party.
Alex Latcham, president of the Senate Leadership Fund, said Griffin regularly discusses campaigns, policy, and party strategy with Thune and closely evaluates individual races before making major contributions.
Griffin has also invested heavily in House races this year.
He donated $5 million in May to the Congressional Leadership Fund, the super PAC aligned with House Republican leadership, along with another $5.5 million to two additional groups supporting Republican House candidates, including one focused on veterans seeking office.
Chris Winkelman, president of the Congressional Leadership Fund, said Griffin's continued financial support has allowed the organization to fully fund key races.
Republicans' most powerful Senate super PAC is setting fundraising records as the party tries to protect its upper chamber majority in the midterms.
The Senate Leadership Fund, the super PAC aligned with Senate Majority Leader John Thune, R-S.D., has amassed $238 million in cash on hand, more than double what the group held at the same point in the previous election cycle under former Senate Majority Leader Mitch McConnell, R-Ky.