Vacancies in elected offices occur regularly at the state and federal levels, and states vary in their approaches to filling them.
Some states hold special elections, while others appoint candidates for the vacant seat. Timelines also vary depending on the level of government and when the vacancy occurs.
State Legislatures
Twenty-five states and four territories fill legislative vacancies through special elections, and 23 states fill them through an appointment process. Appointments may be made by the political party of the vacating legislator, local elected officials, the governor, the legislature as a whole or members of the same chamber and party as the vacating legislator.
Indiana, Tennessee, Washington, D.C., and Puerto Rico use a combination of both methods. Special elections or appointments are used depending on when the vacancy occurred, or the political party affiliation of the vacating legislator. For example, in Indiana, the local party or caucus meets to select a person to fill the vacancy; however, if the person who held the seat was not a member of a major party, then a special election is required.
A few states have introduced legislation this year to change the procedures for filling legislative vacancies. Colorado, which has been reassessing its vacancy-filling process for the last several years, first established an appointment procedure to fill vacancies in 1992 (HB 92-1333). A 2022 law (HB 22-1044) required, at a minimum, for the district’s central committee to be on the vacancy committee. Last month, a new law (HB 1315) changed the procedures for filling legislative vacancies. An appointed legislator may now hold the seat of the vacancy for about a year until an election is required. If someone is appointed to a vacant seat between July 31 of an odd-numbered year and July 30 of the next even-numbered year, an election for the seat will be held in the next general election. If the vacancy happens between July 31 of an even year and July 31 of the next odd year, a special election will be held the following November in the odd year. Only voters from the same political party as the legislator who left the seat, along with unaffiliated voters, are allowed to vote during the election.
Maryland also introduced legislation to make changes to how legislative vacancies are filled in the state. This year, two bills (SB 2 and HB 174) would have amended the constitution and required special elections in certain circumstances. Neither bill passed both chambers, although the Senate bill passed in that chamber with bipartisan support, 44-2.
“The Senate strongly believes, and many members of the House strongly believe, that there should be a more transparent, more accountable, election process,” says Sen. Cheryl Kagan (D), a sponsor of SB 2.
“It is not a partisan issue. There are Republicans who tend to support using special elections to fill legislative vacancies, and Democrats have been on both sides.”
Congress
The U.S. Constitution requires elections to fill congressional vacancies, though there are different requirements for the vacancy election in each chamber. The primary difference is that House vacancies must be filled by a special election and the seat remains empty until that election; in the Senate, a vacancy may be filled temporarily by an appointment until the next general election, or the governor may call a special election to fill the vacancy.
U.S. Senate
Before 1913, state legislatures held the power to elect U.S. senators, a power that extended to filling any vacancies that arose. With the passage of the 17th Amendment in 1913, however, this changed. The Constitution now requires that the office of U.S. senator be filled by a direct vote of the people of each state, and when vacancies arise, they must also be filled by election.
States apply this constitutional requirement in slightly different ways: The remainder of the term is filled either at the next general election or at a special election called for the specific purpose of filling the office. In many states, governors may also appoint a temporary successor to fill a seat until the vacancy election takes place.
Since the ratification of the 17th Amendment, 208 appointments have been made to temporarily fill vacant U.S. Senate seats. Thirteen senators in the current Congress first took their seat through appointment to fill a vacancy. Eleven of these senators went on to win the election for the seat for the remainder of the term or a succeeding term, and two appointed senators have not yet faced election.
This year, the Kansas Legislature passed a law (SB 105) addressing who can be appointed to fill a U.S. Senate vacancy. Beginning July 2025, a U.S. Senate appointee must be of the same political party as the vacating member. Kansas will join nine other states with a similar requirement.
U.S. House
As previously stated, U.S. House vacancies are federally required to be filled by an election. How and when that election occurs is up to the state. Following a vacancy, a state executive—usually the governor—issues a writ or a proclamation for a special election. Some states set a timeline for when the writ must be issued: Mississippi’s at the long end with 60 days after a vacancy occurs; in Minnesota, the writ must be issued just three days after the vacancy.
After the special election is ordered, states have varying timelines for holding the special election, or in some cases, the special primary. There may be further specifications for the special election if it falls within a certain time of a scheduled primary or municipal or general election. For example, if the vacancy occurs in Oklahoma during an even-numbered year, the regular primary, runoff or general election may serve as the special election to fill the unexpired term. In Vermont, if the vacancy occurs within six months of the general election, the special election can be held at the same time as the general election.
Other states do not have timelines for when vacancies must be filled. Vacancies in Texas must be filled “as soon as possible after the vacancy occurs” but have no other requirements. In March, Texas Rep. Sylvester Turner’s unexpected death created a vacancy in the state’s 18th Congressional District, located in Harris County. Texas has no statutory timeline, but Gov. Greg Abbott designated a Nov. 4 special election, and the seat will remain vacant until then. Each state determines its process for filling U.S. House vacancies, and no two states are exactly the same.
For more on filling vacancies, visit NCSL’s resources for procedures in legislatures, the U.S. Senate and the U.S. House.
Katie King, Brenna Nelson and Camilla Rodriguez Guzman are part of NCSL’s Elections and Redistricting Team.