Democrats strongly favored to take the House, Senate tilts Democratic in our new election forecast (crosspost)

Our brand-new election forecast for the 2026 congressional midterms puts Democrats at above even odds to take control of both chambers

Today’s the day we’ve all been waiting for. If you’re reading this, that means we finished dotting our i’s and crossing our t’s and just published our shiny, state-of-the-art 2026 congressional election forecast over at FiftyPlusOne. 🎉

As of 6:00 AM Eastern on August 3, 2026, we give the Democrats an 85% chance to win the majority in the U.S. House of Representatives and a 55% chance to win control of the Senate (which we define as 51 seats or more, unless an independent wins in Nebraska, Montana, Idaho, or South Dakota — unlikely, but not impossible).

Because our forecast simulates elections for both chambers in one unified model, we can also calculate the probabilities of either party controlling both chambers after Nov. Democrats win control of both the House and Senate in just over 50% of simulations, whereas Republicans prevail in less than 12%.

You can read more about the initial results of our forecast in my model launch post over at 50+1. The forecast itself lives here, and here’s an extremely detailed methodology write-up of how it works.

This project is the culmination of months of combined effort by Katie Marriner, head of visualization and engineering; Mary Radcliffe, head of research and singular in her knowledge of the polling landscape; and myself (I do the math and, nominally, direct our editorial output).

Our (50+1’s) coverage of the forecast is mostly going to stay over there; the general idea is that anything derived from the team’s efforts stays there where it benefits the whole team, as long as the tone is a match for 50+1. I make isolated exception to this when a post is better suited for Strength In Numbers (to keep things above board, SIN even pays the fair-market rate for a reusable data license from 50+1).

But I did want to take some space on the newsletter today to write a few more personal words about this project and what it means to me. I think our forecast is special compared to the competition for a few reasons.

First, we have custom charts that work with fast, bespoke web design. In a world of Datawrapper charts and vibe-coded Substack embeds, Katie has done a remarkable job producing an original, functional interactive website for the forecast — and she has done it all on her own. (The rest of the site, with the polls tables and averages, is also Katie’s handiwork.) Unless you’ve built a data interactive like this you cannot comprehend how much effort it is, so Katie deserves a lot of credit for not just getting things working but also making them look nice. We’ll be adding more great charts from Katie over the course of the election.

Second, speed. One of the things 50+1 promises readers and data subscribers is pure, raw speed. Mary enters pretty much all the data that flows through our website, except for election season when we hire help and she “only” enters 80–90%, and is unmatched in her ability to get complete structured data out into the world. Our forecasting system is able to update in close to real time with this data operation Mary has built. It’s so fast and comprehensive that multiple competitor outlets, not to mention political and financial clients, now rely directly on 50+1’s data streams for their operations. (Others watch our site’s HTML for changes then copy us without giving us credit.)

Third, the model. I’ve spent the better part of the last 12 years building polling averages and election forecasting systems, and this new forecast is by far the most statistically satisfying and comprehensive yet. It combines learnings from many different places — from academic political science and financial time series analysis to Bayesian modeling and traditional machine learning — to deliver a model that is well predictive on unseen data and robust to researcher specification and overfitting. Like the website, building a production, public forecasting system of this scale is also one of those challenges that you don’t fully appreciate until you’ve tried it yourself. If you want to understand more of what I mean, go read the 10,000-word methodology post on the site. (If you can believe it, it’s a lot shorter than our internal docs.)

And finally, culture. Aside from the Associated Press and New York Times, 50+1 has more former employees of FiveThirtyEight than any media outlet. Including independent contributors, there’s six of us — at a 100% hit rate! I personally think that it’s partly thanks to our shared time there that we have a hardcore culture of showing our work, treating our readers like adults, and being honest about what we don’t/can’t know (instead of selling you certainty we don’t have for clout). And while some core components of our modeling have to stay proprietary, we are open-sourcing as much as we can, including as of today the forecast’s full backtesting record — all in the name of transparency.

Plus, nobody else is doing as much as we are to keep public, transparent polling aggregation — of horse race and issues polls — alive. Just check out our polls page. Honestly a big part of our approach is that we just care more about accurately reflecting public opinion and uncertainty than pretty much anyone else. Katie, Mary and I all run 50+1 as a side project (four gals and have other full-time jobs that pay the bills. We’re literally doing this for the love of the game.

So go on and head over to 50+1 and check out our new 2026 election forecast (RIGHT NOW GO GO GO). I would start here to get your bearings on what the model predicts right now, then go to the full site to explore your favorite races, then read the methodology if you’re a real sicko. It’s a good way to burn a few cups of coffee. (I certainly drank my fair share writing it.)