ANALYSIS — The smallest initial Senate battleground in history (probably) is good news for Republicans (probably).
At this early stage of the 2026 cycle, Inside Elections rates just five senators as vulnerable, including three Democrats (Georgia’s Jon Ossoff, Michigan’s Gary Peters and New Hampshire’s Jeanne Shaheen) and two Republicans (Maine’s Susan Collins and North Carolina’s Thom Tillis).
Recent cycles have shown a strong correlation between how a state votes for president and who it sends to the Senate, putting Ossoff, Peters and Collins in electoral danger because of the 2024 results (Donald Trump won Georgia and Michigan, while Kamala Harris won Maine). Harris won New Hampshire and Trump won North Carolina, but both states remain competitive.
Everything else looks like a stretch for both parties. It’s hard to imagine Republicans winning in Colorado, Minnesota, New Mexico or Oregon, while Democrats need a lot to go right to seriously compete in Alaska, Florida, Iowa, Ohio or Texas.
At the beginning of a cycle, Inside Elections rates races as either Battleground or Solid. We’ll move to the traditional competitive categories (Toss-up, Tilt, Lean and Likely) later in the cycle.
Five seats represents the smallest initial Senate battleground going back to 1994, when The Rothenberg Political Report (Inside Elections’ predecessor) first started rating races.
The previous smallest initial Senate battleground was 2008, incidentally the same class on the ballot next year. Seven seats were rated as competitive in January 2007, including five Republicans (Collins, Wayne Allard of Colorado, Norm Coleman of Minnesota, Gordon Smith of Oregon and John Sununu of New Hampshire) and two Democrats (Tim Johnson of South Dakota and Mary Landrieu of Louisiana).
The average size of the initial Senate battleground going back 30 years is 13 seats. In the past decade, the average initial battleground was nine seats, the same number at the beginning of the 2024 cycle.
A small battleground benefits Republicans and their new majority. Not only did Republicans win control of the Senate in 2024, but they may also be insulated from a difficult midterm election thanks to gains made last year.
With a target-rich map of Senate races in GOP-leaning states and a strong performance by Trump at the top of the ticket, Republicans flipped four seats last fall. That was two more than they needed for the majority (or three more, with control of the White House). They also came within a few points of gaining four additional seats (Michigan, Wisconsin, Nevada and Arizona), which would have been a catastrophic result for Democrats.
At the outset, Democrats will struggle to gain the four seats they need for a Senate majority. They have to win both of their initial takeover opportunities — including defeating Collins, one of the Senate’s most formidable incumbents — defend all their own seats and then gain two more seats currently considered out of reach. To put it another way, if Democrats were to win all five of the races initially rated as competitive, they’d still be two seats short of a majority.
Republicans might struggle to turn out the Trump coalition when he’s not on the ballot, and the president’s party usually suffers losses in midterm elections, but that trend has been more noticeable in the House. The party holding the White House has gained at least one Senate seat in three of the past six midterm elections, including 2018 (when Republicans netted two seats) and 2022 (when Democrats gained a single seat).
The bottom line is that Democrats need the battleground to expand, but it won’t be easy. It would take a combination of strong challengers and a positive political environment, and just one of those factors won’t be sufficient to overcome the partisanship of the solid states. And as 2024 demonstrated, there’s a lower ceiling on the value of a candidate’s personal political brand in a state friendlier to the opposing party, which should temper expectations of the more flashy potential recruits.
With that dynamic, if the battlefield does expand, it would likely only do so in one direction, as political momentum only moves one way.
For Democrats looking for a glimmer of hope, 2008 offers an example of how a cycle can evolve. A Senate battleground that began with five vulnerable Republicans and two vulnerable Democrats ended with 12 vulnerable GOP seats and just one Democratic seat. Republicans lost all their initially vulnerable seats, except for Collins, as well as open races in New Mexico and Virginia and incumbents in North Carolina and Alaska on their way to a net eight-seat loss in the continued backlash against President George W. Bush that had begun two years earlier.
A similar dynamic could develop against Trump and the Republicans, but it’s certainly not a guarantee. Partisanship is even stronger these days, and there are fewer persuadable voters, making it difficult to expand the map.
Senate Republicans begin the cycle with the advantage to hold the majority in two years.
