I’ve been doing a little history search about wave elections, which led me to this commentary at New York on the Senate landscape for 2026:

It says a lot about the evolving conventional wisdom on the 2026 midterm elections that professional contrarian Harry Enten of CNN felt the need to explain that Democrats don’t exactly have a lock on flipping control of the U.S. Senate in November:

“Right now, Dems have a math problem in taking back the Senate. They need a net pickup of 4 seats & lead in 1 GOP held seat (NC). Rest are ties or GOP ahead. Problem is the fundamentals…. Median of key 6 states: GOP with +6 on generic ballot. 53% say Dem party too far left.”

I might quibble a bit with his specific analysis. The generic ballot is hardly a reliable guide to Senate races. It mostly just confirms what we already know: Democrats need to flip some red-state Senate seats to gain control thanks to an adverse landscape. So it means winning in places where swing voters lean Republican. It’s doable only with the right overall environment (a midterm election with an unpopular Republican in the White House) and a state-by-state advantage in candidate quality.

But it is doable, as recent history has shown. And you don’t have to go back to those times in the 20th century when widespread ticket splitting meant tons of senators could hold seats in enemy territory, thus becoming vulnerable to the occasional intense partisan wave or realignment.

Even this century, “wave” elections have made the “fundamentals” Enten cites largely irrelevant, or at least limited. In 2006, an election year when a second-term Republican president had become very unpopular (sound familiar?), Democrats executed a net gain of six Senate seats and flipped the chamber. More remarkable is that, two years later, when the Bush presidency ended and the country sank into a financial crisis, Democrats won another eight net seats. For a brief moment, Democrats held a Senate supermajority (hard even to imagine today) until Republican Scott Brown won a special election in Massachusetts in early 2010. If that seems like a million years ago to you, consider that the 2006 Ohio winner, Sherrod Brown, is back this year as the Democratic nominee seeking to flip the seat of appointed senator Jon Husted, while Scott Brown is running for the open Senate seat of Democrat Jeanne Shaheen in New Hampshire.

Then in 2014, Republicans returned the favor by flipping nine Senate seats and regaining the Senate control they lost in 2006.

What all these Senate-wave years have in common is that the winning party didn’t lose any seats at all. Similarly, the key to Democratic prospects in 2026 may depend as much on whether they successfully defend potentially vulnerable seats in Georgia, Michigan, and New Hampshire as on their ability to win tough races in Alaska, Maine, Ohio, and Texas. Failure to hold their own turf explains why Democrats actually lost ground in the Senate races of 2018 even as they gained 41 House seats and flipped the chamber. Conversely, in 2022 as Democrats lost control of the House, they managed to hang on to Senate control by successfully defending three vulnerable seats and flipping a GOP seat in Pennsylvania.

It all reinforces the fact that Senate races occupy their own political universe in which the broader dynamics — particularly, which 33 or 34 seats happen to be on the ballot in any given election — matter a lot but individual contests do as well. The landscape still favors the GOP in November, but a wave on the level of 2006 (again, an eerily similar moment when you compare the job-approval levels of Republican presidents then and now) wouldn’t be that surprising and could restore Democratic control of the upper chamber.