The 2018 United States Senate election in Missouri took place on November 6, 2018, to elect a member of the United States Senate to represent the State of Missouri, concurrently with other elections to the United States Senate, elections to the United States House of Representatives, and various state and local elections, including Missouri's quadrennial State Auditor election.
Incumbent Democratic Senator Claire McCaskill ran for re-election to a third term. McCaskill easily won her party's nomination, defeating several minor candidates in the primary, while Missouri Attorney General Josh Hawley comfortably won the Republican primary.
The candidate filing deadline was March 27, 2018, and the primary election was held on August 7, 2018. Pollsters predicted a tight race, however Hawley defeated McCaskill on election day by 5.8%, taking 51.4% of the vote to McCaskill's 45.6%, a somewhat larger margin than expected. This resulted in Republicans holding both Senate seats in Missouri for the first time since McCaskill took office in 2007. Hawley was also the youngest incumbent senator at that time and continued to be until the election of Jon Ossoff in 2021.
Democratic primary
Candidates
Nominated
Claire McCaskill, incumbent U.S. Senator
Eliminated in primary
Angelica Earl, former insurance verification specialist
David Faust
Travis Gonzalez, perennial candidate
John Hogan, perennial candidate
Leonard Steinman, perennial candidate
Carla (Coffee) Wright
Endorsements
Results
Republican primary
Candidates
Nominated
Josh Hawley, Missouri Attorney General
Eliminated in primary
Austin Petersen, businessman and Libertarian candidate for presidential nomination in 2016 Brian Hagg Bradley Krembs Tony Monetti, retired bomber pilot and assistant dean of aviation at University of Central Missouri Kristi Nichols, activist and candidate for the U.S. Senate in 2010 and 2016 Ken Patterson, candidate for St. Louis County Executive in 2010 Peter Pfeifer Fred Ryman, Constitution nominee for the U.S. Senate in 2016 Christina Smith Courtland Sykes, veteran and former congressional aide
Withdrew
Camille Lombardi-Olive, Democratic candidate for MO-07 in 2016
Declined
Ann Wagner, U.S. Representative and former U.S. Ambassador to Luxembourg
Aaron Hedlund, economics professor
Paul Curtman, state representative
Eric Greitens, former Governor of Missouri
Vicky Hartzler, U.S. Representative
Todd Richardson, Speaker of the Missouri House of Representatives
Eric Schmitt, state treasurer
David Wasinger, attorney
Marsha Haefner, state representative
Ed Martin, former chairman of the Missouri Republican Party, nominee for MO-03 in 2010 and nominee for attorney general in 2012
Endorsements
Debates
Polling
Results
Libertarian primary
Candidates
Nominated
Japheth Campbell, entrepreneur
Withdrew
Don Donald
Dennis Lagares
Declined
Alicia Dearn, attorney and candidate for Vice President of the United States in 2016 Austin Petersen, Libertarian candidate for President of the United States in 2016 (running as a Republican)
Results
Green primary
Candidates
Nominated
Jo Crain
Eliminated in primary
Jerome Bauer
Results
Independents
Candidates
Declared
Craig O'Dear, attorney
General election
Predictions
Debates
Complete video of debate, October 18, 2018
Fundraising
Polling
with Austin Petersen
with generic Republican
with Vicky Hartzler
with Blaine Luetkemeyer
with Todd Richardson
with Eric Schmitt
with Jason Smith
Results
Sen. McCaskill conceded a few hours after the polls closed on Election Day. Despite performing strongly in the St. Louis suburbs, she ran well behind her 2012 vote in Southeast Missouri, especially in the Lead Belt and the Missouri Bootheel. She also ran poorly in the northern part of the state. Despite McCaskill's loss, Missouri Democrats held the other statewide office that went up for election in this cycle, the office of Missouri State Auditor. Democratic incumbent state auditor Nicole Galloway, who had been appointed to the post in 2015 by then-Gov. Jay Nixon following a vacancy, won a full term in the 2018 State Auditor election.