What is the 2026 Senate class breakdown and which class is up for election?

1. What “classes” mean and which one is on the ballot

The Senate is divided into three staggered classes so roughly one-third of seats come up every two years; senators in Class 2 were last elected in 2020 and are the primary group on the 2026 ballot ^{[5] [6]}. That means the regular slate on November 3, 2026 consists of the 33 Class 2 seats whose new six‑year terms would run 2027–2033 ^[1].

2. The partisan math heading into the cycle

Multiple nonpartisan trackers report Republicans with control of the chamber after 2024 — commonly stated as a 53–47 split with two independents caucusing with Democrats — and they count Republicans as defending the larger share of the 2026 map ^{[7] [8] [9]}. Ballotpedia and Wikipedia both put the regular 33-seat Class 2 map at 20 Republican-held and 13 Democratic-held seats, a partisan distribution that frames 2026 as a defensive year for Democrats and an opportunity for Republicans to expand ^{[2] [1]}.

3. Why some sources say “35” seats instead of 33

The standard answer is that the 33 Class 2 seats are the regular contests, but two additional special elections — to finish terms in Florida and Ohio — are scheduled concurrently on November 3, 2026, which pushes many trackers’ total up to 35 contests that day ^{[3] [4]}. Forecasting sites and aggregators therefore sometimes report 35 seats up because they include those special races alongside the Class 2 slate ^{[7] [10]}.

4. What the map implies politically

Because Republicans are defending more seats on the Class 2 map (20 vs. 13 Democrats), conventional wisdom among forecasters is that Democrats need to flip a net of four seats to regain the majority, while Republicans can afford modest losses and still keep control ^{[11] [12]}. Analysts emphasize specific swing states on the 2026 map — Georgia, Michigan, Iowa, Texas and others — as where control could realistically shift, and they note that only a subset of those Republican-held seats are viewed as competitive ^{[11] [12]}.

5. Disagreement and variation across trackers

Sources agree on the core facts — Class 2 is the regular 2026 class and it contains 33 seats — but they differ in how they present totals because of the special elections. Wikipedia, Ballotpedia and Senate.gov emphasize the 33-seat Class 2 list and the 20R/13D split ^{[1] [2] [5]}, while 270toWin, RaceToTheWH and others commonly headline "35 seats" because they add the two special contests ^{[7] [10] [13]}. Readers should note the distinction between “regular” (Class 2) seats and all contests held on the same day.

6. Limitations and what reporting does not (yet) say

Sources provided here list which seats are on the ballot and the partisan holder counts, and they identify Florida and Ohio specials; they do not provide a definitive, universally adopted single-seat total because presentation choices differ across outlets ^{[3] [4]}. Available sources do not mention final candidate lists for every seat nor do they present an agreed‑upon projection for the chamber’s control in 2027 — those are the products of ongoing forecasting and will change as campaigns develop ^{[12] [14]}.

7. How to read the numbers going forward

For clarity: treat “33 Class 2 seats” as the canonical description of the regular cycle ^{[1] [2]}; treat “35 contests” as shorthand used by some outlets that include the Florida and Ohio special elections happening the same day ^{[3] [4]}. Follow multiple trackers (Senate.gov/Ballotpedia for seat lists; 270toWin/Sabato/Cook for ratings) because each has different emphases — legal status of seats, partisan counts, and probabilistic ratings — and those distinctions explain why headlines sometimes appear inconsistent ^{[5] [2] [9]}.

If you want, I can compile the current list of the 33 Class 2 senators and mark which party holds each seat according to Ballotpedia/Wikipedia and note the two special‑election states cited in these reports.