A runoff election is a second round of voting held when no candidate reaches the threshold required to win outright, which is usually a majority of the vote. The top two finishers from the first round face each other, and the winner of that head to head race takes the seat or the nomination.
Why runoffs exist
In a race with several candidates, someone can finish first with well under half the vote. States that require a majority use a runoff so the eventual winner has been chosen by more than half of the people who turned out in the deciding round. States that do not require a majority simply award the seat to whoever gets the most votes, a rule known as plurality.
Primary runoffs
Nine states schedule runoffs for congressional primaries: Alabama, Arkansas, Georgia, Mississippi, North Carolina, Oklahoma, South Carolina, South Dakota, and Texas. Two of those have distinctive rules. In North Carolina a runoff happens only if the second place candidate requests one. In South Dakota a runoff is triggered only when no candidate reaches 35 percent, rather than a full majority.
A primary runoff decides a party nomination, not the seat. The winner still has to compete in the November general election.
General election runoffs
Three states can send a congressional general election to a runoff when nobody wins a majority: Georgia, Mississippi, and Louisiana.
Louisiana works differently from everywhere else. It does not hold traditional party primaries for Congress. Every candidate from every party appears on one ballot, and if no one clears 50 percent, the top two advance to a runoff even if they belong to the same party.
Runoffs in special elections
Runoffs show up often in special elections, because those races tend to draw crowded fields. When many candidates split the vote, a majority winner in the first round is unlikely, so the runoff becomes the real contest.
What to expect if your race goes to a runoff
Turnout usually drops between the first round and the runoff, sometimes sharply. The runoff is a separate election with its own date, its own registration and absentee deadlines, and its own ballot. If you voted in the first round, you are not automatically counted in the second. Check your state election office for the runoff date and deadlines, and see how to check your voter registration.
Related reading
Terms used here are defined in the glossary. For current races see the 2026 Congressional Elections Tracker and the 2026 Senate elections tracker.
Sources: Ballotpedia, Runoff election. USAFacts, How do runoff elections work.
Last updated September 3, 2026.
