When a U.S. Senate seat opens in the middle of a term, most states fill it quickly by appointment. The appointed senator is a full member of the Senate with the same vote as anyone elected to the job. This is one of the clearest differences between the two chambers of Congress.
Where the power comes from
The Seventeenth Amendment, ratified in 1913, moved Senate elections from state legislatures to voters. It also included a provision for vacancies: the legislature of a state may allow its governor to make a temporary appointment until the people fill the vacancy by election. That is permission, not a requirement, which is why the rules differ from state to state.
What states actually do
Most states have granted their governors that appointment power, so a vacancy is usually filled within days or weeks. A handful of states do not allow an appointment at all and leave the seat empty until a special election. Others allow an appointment but constrain it, for example by requiring the governor to pick someone from the same party as the departing senator, or by requiring the appointee to be a placeholder who does not run in the special election.
How long an appointee serves
An appointment is temporary by design. The appointee serves until the voters settle the seat in a special election, which is usually scheduled for the next regular election date. At that point the winner of the special election finishes whatever remains of the original six year term.
Two things follow from that. First, an appointed senator can serve anywhere from a few months to nearly two years depending on when the vacancy happened. Second, an appointee who wants to stay has to win an election like anyone else, and some never run at all.
Recent examples
Several current senators reached the chamber this way. In South Carolina, Governor Henry McMaster appointed Darline Graham Nordone in July 2026 after Senator Lindsey Graham died, to serve until January 3, 2027. In Oklahoma, Governor Kevin Stitt appointed Alan Armstrong in March 2026 after Markwayne Mullin resigned to join the administration. In Florida and Ohio, seats vacated in 2025 by Marco Rubio and JD Vance were filled by appointment and are on the ballot in 2026 as special elections.
Why the House is different
There is no equivalent power for the House. The Constitution requires House vacancies to be filled by election, so a district can sit without a representative for months. See what happens when a congressional seat becomes vacant for that comparison.
Related reading
See how special elections to Congress work, the 2026 Senate elections tracker, and the glossary. For profiles of all 100 senators, see the U.S. Senators directory.
Last updated September 3, 2026.
