WASHINGTON — Rex Sinquefield was at the U.S. Capitol last month to showcase his own St. Louis Chess Club alongside Missouri lawmakers at the Bipartisan Congressional Chess Tournament.
The event drew both Missouri senators, several of the state’s U.S. House members and even Sen. Ted Cruz, R-Texas.
But if campaign finance history is any indicator, they weren’t there just to see a checkmate — they came to see Sinquefield, one of Missouri’s most influential conservative donors for the past 15 years.
In this midterm election cycle alone, Sinquefield has contributed over $1.5 million to Republican candidates or Republican-aligned committees. The bulk of that sum comes from a $1.1 million contribution to Grow the Majority PAC, a joint fundraising committee launched by House Speaker Mike Johnson, R-La., to seed Republican House campaigns across the country.
It is the second largest contribution from any individual in Missouri this election cycle. His wife, Jeanne Sinquefield, holds the third largest contribution — a separate $1 million donation to Grow the Majority.
The largest contribution of the cycle so far came from Michael Rayner, a St. Louis-area businessman who is part of the family that owns Cargill, an international agribusiness corporation. Rayner spent $2.5 million to seed the now-terminated Save Missouri Values PAC. That money currently sits unspent in Alabama-based Fight for America PAC.
Rex Sinquefield also contributed $260,700 to the National Republican Senatorial Committee, NRSC, across four separate transactions since 2025. Led by U.S. Sen. Tim Scott, R-S.C., the NRSC is devoted to electing Republicans to the U.S. Senate.
The mega-donor continued his longtime support for U.S. Sen. Eric Schmitt, R-Mo., with a $250,000 donation to Winning for America fund, a Schmitt-linked joint fundraising committee. While the senator is not up for reelection until 2028, Schmitt can spend the money on other senators’ campaigns to boost his chances at earning a leadership position within the Senate down the road.
In Schmitt’s original bid for Senate, Sinquefield sent $1 million to a PAC opposing Schmitt’s main Republican opponent, former Missouri Gov. Eric Greitens. To date, Sinquefield has given $455,800 to Schmitt-linked committees.
Sinquefield, 81, donated directly to three other committees associated with specific candidates this cycle: $15,000 to U.S. Rep. Bob Onder, R-Mo., $12,000 to U.S. Rep. Ann Wagner, R-Mo., and $2,500 to Scott.
Across all midterm congressional races in Missouri, Republican candidates have raised over $13 million — more than double their Democratic counterparts.
Sinquefield has served on the boards of the Missouri Botanical Garden, Missouri History Museum, Opera Theatre of Saint Louis, Saint Louis Art Museum, Saint Louis Symphony and Saint Louis University beyond his presidency of the St. Louis Chess Club.
Sinquefield did not accept the Missourian’s request for an interview.
Sinquefield, now retired, established his fortune as a co-founder of Dimensional Fund Advisors — an investment firm that manages over $1 trillion in assets today.
Born in St. Louis, he spent much of his childhood at Saint Vincent Home for Children. He graduated from Bishop DuBourg High School, and attended seminary school for three years before shifting his education to philosophy and business at St. Louis University. From there, he earned a master’s degree in business administration from the University of Chicago.