What Senate vacancies and gubernatorial appointments between 2024 and 2026 affected party balance, and how were those appointments decided?

1. Major 2024–2026 vacancies that mattered to party control: Rubio (FL) and Vance (OH)

Florida Republican Marco Rubio resigned January 20, 2025, to join the presidential administration, and Governor Ron DeSantis appointed fellow Republican Ashley Moody to hold the seat until a special election coinciding with the 2026 general election, keeping the state’s Senate seat in Republican hands while a special election is scheduled ^[2]. Ohio’s Republican Senator J.D. Vance resigned January 10, 2025, after being elected vice president, and Governor Mike DeWine appointed Republican Lieutenant Governor Jon Husted on January 17, 2025, to serve until voters choose a successor — another appointment that maintained the GOP’s numerical advantage in the chamber ^[1].

2. How those appointments were decided: state law, governor discretion, and timing rules

Both appointments followed state procedures that allow governors to name interim senators; the Seventeenth Amendment permits state legislatures to empower governors to make temporary appointments and requires a subsequent election to fill the remainder of the term, and Congressional Research Service reporting lays out how many states authorize appointments that last until the next general election versus those that require expedited special elections ^{[3] [6]}. Ballotpedia and state summaries show most states provide for gubernatorial appointments but with important variations in timing and whether an appointee must be of the same party as the departing senator; those statutory differences shape a governor’s options and political calculations when naming a temporary successor ^{[4] [7]}.

3. State-by-state exceptions and the contested arithmetic of appointment authority

Not all states permit appointments: reporting flags Kentucky, North Dakota, Oregon, Rhode Island and Wisconsin as states that fill Senate vacancies only via special election, and other sources list slightly different tallies of appointment states — reflecting either legislative changes or differing cutoffs used in analyses ^{[8] [4] [5]}. The Congressional Research Service and NCSL provide granular tables showing which states require accelerated specials, which allow appointments through the next general election, and which impose party‑matching or no‑run conditions — legal contours that can blunt or amplify a governor’s partisan advantage ^{[3] [9]}.

4. Effect on Senate balance and the 2026 battlegrounds

Republicans entered the 119th Congress with a 53–45 majority, and the two 2025 gubernatorial appointments in Florida and Ohio replaced Republicans with Republicans, leaving the partisan arithmetic unchanged while deferring the decisive test to the 2026 special races and regularly scheduled contests ^{[10] [2] [1]}. Because many appointments are temporary until a 2026 special election, governors can preserve short‑term control but not permanently alter the long‑term partisan map without winning the subsequent contests; analysts and political actors therefore view appointments as stopgaps that can confer incumbency advantages but not guaranteed flips ^{[3] [2]}.

5. Where reporting diverges and what still isn’t settled

Sources disagree on the precise number of states that allow appointments (CRS/Library of Congress tables versus Ballotpedia and Pew counts), and some state statutes impose party‑matching or timing constraints that complicate simple categorizations — a reminder that “gubernatorial appointment” is not a single mechanic but a patchwork of state rules with real political consequences ^{[3] [4] [5]}. Available reporting documents the appointments that preserved Republican seats in 2025 and the scheduling of 2026 special elections, but does not provide a comprehensive list of every vacancy in 2024–2026 beyond those high‑visibility cases cited above ^{[2] [1]}.