The 2024 race to control the House couldn't be tighter

We're now less than a month out from the 2024 election, and most signs point to a closely fought race that could prove to be a nailbiter. That's true of the presidential contest between Vice President Kamala Harris and former President Donald Trump, but it's also the case in the national contest for control of the U.S. House of Representatives. With Republicans holding just a 221-to-214 majority (grouping vacant seats with their previous party), Democrats need only a four-seat net change in their favor to regain a one-seat edge in the House.

Given those narrow margins and the broader competitive political environment, 538's new forecast of the House understandably gives each party just about a 1-in-2 shot of controlling the chamber after the 2024 election — making the race a true coin flip. Much like the presidential contest, the outcome here is very uncertain.

This projection is produced using a number of data points, starting with an average of national generic ballot polls for House races — reweighted based on pollster ratings and adjusted for potential statistical biases stemming from the corresponding pollster and the poll's methodology and population — along with any available public polling for individual House races (though that tends to be sparse). The model also incorporates other quantitative and qualitative data, including expert race ratings and a variety of non-polling factors that we call the "fundamentals" — such as how blue or red a district is, incumbency, and a candidate's electoral history and fundraising. (Check out the full methodology for our House forecast for a deep dive into how it works.)

Looking at the overall picture, evenly split probabilities for which party will control the House don't necessarily mean that the eventual result will be a single-digit majority for one party or the other; rather, there is a sizable range of outcomes, with each party coming out on top in around half of them. Because election trends in similar-looking parts of the country tend to align with each other, a better-than-expected performance for one party in certain types of districts could augur well for them in other seats and produce a double-digit seat majority. In about 2-in-3 simulations, either the Democrats or Republicans end up with at least a 10-seat advantage after the 2024 election. Nevertheless, that leaves around a 1-in-3 chance that the majority will have less than a 10-seat edge, and such a result would be in keeping with recent elections, which have tended to see a more closely divided House.

Digging into individual races, most seats in the House are uncompetitive, so the contests that will decide the House majority make up a very small proportion of the overall map. In about 345 of the chamber's 435 seats, one party or the other has a better than 95-in-100 shot of winning, per the 538 forecast. Yet even among the roughly 90 potentially competitive seats that leaves, few of those are likely to be that competitive, with the forecast viewing most as likely to go to one party or the other.

Ultimately, the universe of seats that will play the largest role in determining which party wins a majority includes 26 seats. In each of these contests, neither side has better than a 75-in-100 chance of victory — the forecast views each as a toss-up or as leaning only slightly toward one party or the other.

Republicans find themselves defending more of this battleground turf than the Democrats do, which is unsurprising given that they flipped a number of these seats in the 2022 midterm elections — 9 of the 17 GOP-held seats on this list have incumbents first elected that year. Many of the most competitive seats the GOP is defending are also in "crossover" districts, where the party that holds the seat is different from the one that would have carried it in the 2020 presidential election. While 2020's presidential results of course may not be fully predictive of what we'll see in 2024, crossover districts matter because a seat's presidential vote is a strong baseline indicator of which direction the district is likely to lean, especially nowadays given our sharply polarized politics. Few House members these days win elections in districts that their presidential nominee doesn't also carry in the same election cycle, with the total hitting a recent low of 16 seats in 2020 — just 4 percent of all 435 districts.

Simply put, the ability of incumbent House members (or the incumbent party) to outperform their party's presidential candidate may be pivotal in many of this year's key contests — and to deciding overall control of the House. Looking at the 26 most competitive races, President Joe Biden would have outperformed Trump in 12 of the 17 Republican-held seats, including five where he beat Trump by 10 or more percentage points. In fact, the five GOP-held seats that our forecast rates as "lean Democratic" are all seats that Biden would have carried. Democrats do have their own crossover seats to defend, though, as Trump carried four of the nine that they're defending. Tellingly, all four are toss-up seats.

Outside of these highly competitive seats, a few are likely to change hands due to the fact that five states redrew their House maps ahead of the 2024 election. That's notably affected the probable outcomes in a handful of seats — although the parties may end up making a roughly even trade from these changes. Specifically, three Democratic-held seats in North Carolina look certain to flip to the GOP (the 6th, 13th and 14th Districts), while a fourth (the 1st District) still favors Democrats but is a Republican target. Yet Democrats are likely to flip two redrawn seats in other states (Alabama's 2nd and Louisiana's 6th) after federal courts ruled those states' maps violated the Voting Rights Act by limiting the opportunities for Black voters to elect candidates of their choice. Additionally, redistricting in New York has put Republican Rep. Brandon Williams (22nd District) in a tough spot, as the forecast gives him less than a 1-in-4 chance of holding onto a somewhat bluer, Biden-won seat.

Although they might look less competitive, probability suggests that some seats beyond the ones we've reviewed so far could still potentially switch hands. In virtually every election, one party or the other tends to pull off a lower-probability win, often flipping what appeared to be a safe seat for their opponents. In 2022, Democrat Marie Gluesenkamp Perez won Washington's 3rd District in a race that 538's forecast gave less than a 1-in-20 shot of victory. In 2020, Republicans flipped both Florida's 27th District and Iowa's 1st District while having at best a 1-in-6 shot of capturing either seat. With that in mind, there could be a surprise or two (or more) in store for us among some of those 55-odd seats in which one party has between a 75- and 95-in-100 shot in winning — or perhaps even in a district that seems even more secure for one party.

Lastly, our forecast highlights another interesting facet of the contest for the House: With national politics so closely divided, it's quite possible that the party that wins more votes across all 435 House races won't actually win a majority of seats. Just as the Electoral College victor in presidential races doesn't always win the national popular vote, a party's votes in House contests can potentially be distributed more efficiently across districts to maximize the potential seat gains. Our forecast finds that the party that wins fewer votes nationally captures a majority in about 1 in 8 simulations, with Republicans having a much better chance of claiming such an outcome than Democrats.

All else being equal, each party would be better off if their presidential contender can put together a sizable lead as the votes are tallied on Election Night. The potential coattails from the presidential winner could pull a few party-mates downballot across the finish line in some of these tough congressional contests. But at this point, our forecast suggests the race for control of the House really couldn’t be tighter. And considering the time it will take to count votes, it might take many days — even weeks — to discern which party has captured the House.