Senate
Seats that changed party, and races with independents
- Top rail House, bottom rail Senate
- Democratic majority
- Republican majority
- Dashed: 2026 is provisional
- Before 2000: not available to select
Seats that flipped
Senate seats won by a different caucus from the one holding them, 2000 to 2026.
- Above the line: seats flipped to the Democrats
- Below: seats flipped to the Republicans
Seats that changed party in 2024
In 2024, 4 Senate seats changed party, all to the Republicans. One more seat changed party label but stayed with the same caucus.
| State | Previous caucus | New caucus | Winner | |
|---|---|---|---|---|
| Arizona | DemocraticD | DemocraticD | Ruben GallegoLabel change: Independent to Democrat, same caucus | D +2.4 |
| Montana | DemocraticD | RepublicanR | Tim Sheehy | R +7.1 |
| Ohio | DemocraticD | RepublicanR | Bernie Moreno | R +3.6 |
| Pennsylvania | DemocraticD | RepublicanR | Dave McCormick | R +0.2 |
| West Virginia | DemocraticD | RepublicanR | Jim Justice | R +41.0 |
Source: MIT Election Data and Science Lab, U.S. Senate statewide returns; official state results for races the dataset lacks.Data as of
Senate races involving independents
Races from 2000 to 2024 where an independent held or won the seat, or where a seat changed party label without changing caucus. Only a change of caucus counts as a flip.
| Winning party | Race | Seat held by | Won by | Counted as a flip |
|---|---|---|---|---|
| Connecticut 2006 | Joseph I. LiebermanDEM | Joseph I. LiebermanINDcaucused with Democrats | No | |
| Vermont 2006 | James JeffordsINDcaucused with Democrats | Bernard SandersINDcaucused with Democrats | No | |
| Connecticut 2012 | Joseph I. LiebermanINDcaucused with Democrats | Christopher S. MurphyDEM | No | |
| Maine 2012 | Olympia J. SnoweGOP | Angus KingINDcaucused with Democrats | Yes | |
| Arizona 2024 | Kyrsten SinemaINDcaucused with Democrats | Ruben GallegoDEM | No | |
| West Virginia 2024 | Joe ManchinINDcaucused with Democrats | Jim JusticeGOP | Yes | |
| Georgia 2000 special | Zell MillerDEMappointed | Zell MillerDEM | No | |
| Pennsylvania 2010 | Arlen SpecterDEMswitched | Pat ToomeyGOP | Yes |
Source: MIT Election Data and Science Lab, U.S. Senate statewide returns; US Senate Historical Office for party switches and appointments. Names link to the Biographical Directory of the United States Congress.Data as of