Which Senate seats are up for election in 2026?
Executive summary
The 2026 U.S. Senate map will include the regularly scheduled Class 2 cycle — 33 seats — plus at least two special elections that some outlets count, producing either 33 or 35 contests depending on the source (Wikipedia, Ballotpedia, Reuters list the 33 Class 2 seats; 270toWin and other outlets count 35 including special elections) [1] [2] [3]. Class 2 is currently held by more Republicans than Democrats (about 20 R to 13 D), making the map broadly favorable to Republicans but leaving several marquee and competitive races to watch [1] [4] [5].
1. Which seats are up: the technical picture
By law the Senate is divided into three classes; the regular 2026 cycle is Class 2 — the senators whose six-year terms expire in January 2027 — so 33 regularly scheduled seats are on the ballot in November 2026 [1] [2] [4]. Federal and nonpartisan compilers such as Ballotpedia and the Senate's official Class II page list those regularly scheduled seats as 33 [2] [6].
2. Why some outlets say “35” — special elections and counting differences
Several election trackers and advocacy groups count additional special elections that will be held the same day as the general election — notably in Florida and Ohio — and arrive at 35 total contests for 2026 [3] [7]. That explains the discrepancy across reputable sources: 33 is the number of regular Class 2 seats; 35 is the practical number of Senate contests some analysts expect once state-level special elections are added [3] [7].
3. Partisan balance of the seats up for grabs
The regularly scheduled Class 2 slate is tilted toward Republicans: multiple sources count roughly 20 Republican-held seats versus 13 Democratic-held seats in the Class 2 group, producing an uphill map for Democrats seeking to retake the chamber [1] [4]. Analysts say Democrats need a net gain of roughly four seats to win the majority under current post-2024 math — a steep climb given which states the Republican seats are in [8] [9].
4. Why the map favors Republicans — geography and incumbency
Commentators and early ratings note that most Republican-held seats up in this cycle are in states Donald Trump carried decisively in 2024, which reduces Democratic opportunity in many races [8] [7]. That structural advantage is why outlets such as Thompson Coburn and political forecasters describe the 2026 map as “Republicans’ to lose” and why conventional wisdom views Democrats’ path as narrow [8].
5. Key races and retirements to watch
Reporting highlights several marquee contests and open seats that could swing control or at least alter the margin: Maine’s open or competitive seat where Republican Susan Collins is a focal point; Georgia (Jon Ossoff’s seat) and other swing states where Democrats are defending vulnerable incumbents; and open-seat contests created by announced retirements [1] [5] [9]. Reuters and other outlets identify roughly a half-dozen races likely to attract national attention and funding [5] [9].
6. How forecasters treat the map today
Cook, Sabato’s Crystal Ball, and similar rating shops are publishing state-by-state ratings; they start from the structural advantage described above but diverge on which specific seats are toss-ups versus lean or safe [10] [11]. That means control is not preordained; targeted pickups in a few competitive states could shift the outcome, which is why both parties are already planning recruitment and fundraising [10] [8].
7. Limitations and differences in reporting
Sources disagree only in count when special elections are included; primary factual claims — 33 Class 2 seats on the regular ballot and the partisan tilt of that class — are consistent across authoritative listings [1] [2] [4]. Available sources do not mention a definitive, single list of all 33 (or 35) individual states consolidated in one place in the provided excerpts; readers should consult the Senate’s Class II page or Ballotpedia for state-by-state rosters [6] [2].
8. Bottom line for readers
Expect 33 regularly scheduled Senate races in November 2026 (Class 2), with at least two additional special elections that some outlets include, yielding 35 contests in some counts; the Class 2 slate currently favors Republicans roughly 20–13 and gives Democrats a difficult but not impossible path to a net gain of around four seats to win the majority [1] [3] [8]. Check Ballotpedia, the Senate’s Class II listing, and major ratings sites for the evolving state-by-state picture as candidates and special-election rulings are finalized [2] [6] [11].