Incumbent U.S. Rep. Bob Onder and Bethany Mann are set for a rematch in November after both won their primaries in the 3rd Congressional District race.
Onder won the Republican primary to secure his party’s nomination, as Columbia and southern Boone County voters cast ballots in a newly drawn congressional district. He edged out John G. Fraser for the spot on the general election ballot.
Bethany Mann was declared the winner in the Democratic primary, defeating Tommy Holstein after candidate Paul Wilson withdrew from the race.
In 2024, Onder defeated Mann by 26% to earn the congressional seat.
The election marked the first primary for most Columbia voters after the city was shifted almost entirely from the 4th Congressional District. The new congressional map was approved by the Republican-controlled Missouri General Assembly during a special legislative session last fall at the urging of President Donald Trump.
The new 3rd District stretches from central Missouri to the St. Louis suburbs. Residents north of Columbia across Boone County are now part of the 5th Congressional District, which extends north and west toward Kansas City.
The new maps reflected a Republican goal of dividing Democratic votes to add another Republican seat to Missouri’s congressional delegation, which currently has a 6-2 Republican majority.
Republican lawmakers argued that the map better reflects Missouri’s electorate, while Democrats and voting rights advocates challenged it as an unconstitutional, partisan gerrymander. After months of legal challenges, the Missouri Supreme Court upheld the map, allowing it to be used in the primary election.
Onder began his political career in 2006 when he was elected to the Missouri House of Representatives. He won election to the Missouri Senate in 2014, where he served as assistant majority floor leader and became known as one of the chamber’s leading conservative voices on taxes, abortion and government spending.
He served two terms before leaving the Senate in 2022 because of term limits.
As a U.S. representative, he serves on the House Judiciary Committee, the House Transportation and Infrastructure Committee, and the House Education and Workforce Committee.
In Congress, Onder has continued to advocate for positions he championed in the state legislature, including opposition to illegal immigration and abortion, protecting gun rights and promoting lower taxes. Onder has also supported Missouri’s congressional redistricting effort.
“We are a Republican state,” Onder said in an interview with St. Louis Public Radio. “Republicans have super majorities in the Missouri House and the Missouri Senate. Republicans hold all of our statewide elected offices, including, of course, governor. I believe that we should pass a congressional map that reflects the values of the state of Missouri.”
Mann, who lives in St. Peters, is a technology specialist and works with laboratories in the agriculture, energy, pharmaceutical and environmental industries. She earned a degree in chemistry and began her career as an intern with the U.S. Environmental Protection Agency before moving into the private sector.
She said her campaign has been centered on strengthening Missouri’s middle class through investments in education, infrastructure and affordable healthcare. She supports fully funding public schools, expanding broadband access, repairing roads and bridges, and increasing federal investment in rural infrastructure.
Mann also supports expanding affordable healthcare access, improving mental health services, protecting reproductive rights and increasing access to telehealth.
She also advocates for an expansion of voting access through mail-in ballots and additional early voting opportunities, renewable energy initiatives and environmental protections.
When Onder and Mann face off in the November general election, voters in the newly overhauled 3rd Congressional District will see their first congressional contest under the new district boundaries.