Most coverage of the 2024 Senate elections frames the race for the majority as resting on a knife’s edge. The logic, on paper, is sound — after all, Republicans need to flip at least two seats to take full control at a time when an exceptionally weak nominee, with a history of elevating extremely problematic candidates, is poised to head their ticket.
We do not completely agree with this train of logic, however, mainly due to differences over how to quantify uncertainty. In common electoral discourse, there is a tendency to treat things as either “safe” or “tossups”, instead of “competitive” and “uncompetitive”, and while the Senate merits description as competitive, it is a far cry from a true tossup.
This is because every single one of the ten plausibly competitive Senate elections is in a state that was more Republican than the nation as a whole in 2020, and three Democratic seats (West Virginia, Montana, and Ohio) are in states that are now very Republican.
Put another way, Democrats can afford to lose a net total of one seat in the 2024 elections. However, they are defending eight seats in states that lean to the right of the nation, and one of them (West Virginia) is a virtual lock to flip Republican, thanks to Joe Manchin’s retirement. This almost eliminates their margin for error, meaning that they will need to hold all of their remaining seven seats (barring a currently unlikely upset in either Texas or Florida) and win the presidency so that the Vice President can serve as a tiebreaker in their favor. In the current political environment, that may be somewhat difficult.
Readers may point out that a tied national environment is usually not a great frame to use in presidential cycles, given that Republicans have won the popular vote exactly once in the last eight elections. But with Biden and Trump currently tied in national polling as we head into 2024, it is now an outcome whose implications are at least worth considering.
To be clear, Democrats will enjoy some advantages from fundraising and incumbency, and this might be enough to carry them across the line in several states. They also have several fairly strong incumbents running, which should give them a bit of an additional boost. But even after factoring in the above-average strength of their incumbents, the math looks very rough for the party at the moment.
If election day mirrored current polls, the map below shows what our fundamentals-based model suggests the Senate elections would look like after factoring in fundraising, state leans, current statewide environments, incumbency, and prior incumbent overperformance (but without factoring in challenger strength — more on that in a minute).
As a reminder, the model’s output does not reflect our current ratings, for reasons we’ll describe below, but it does serve as an instructive exercise in demonstrating just how difficult the baseline picture is for Democrats given the current polling environment, and how strongly they’d need to defy the odds again in order to win the majority. In fact, it is arguable that Democrats winning the Senate in 2024 may be a bigger feat than it was in 2022, when the party defied expectations and historical trends to gain a seat in the upper chamber.
There are good reasons to think that this picture could get much friendlier for Democrats. For starters, Republicans may nominate some exceptionally problematic candidates in Ohio, Nevada, Michigan, and Wisconsin. In this case, the latter three would be relegated to the edge of the board for Republicans, while the former might become a tossup (or even a Democratic-tilting race). Additionally, if former gubernatorial candidate (and prominent election denier) Kari Lake wins the GOP nomination in Arizona, Kyrsten Sinema could pull more from Republicans in a three-way race, making Gallego the clear and obvious favorite in a race that would otherwise have been a tossup.
All of these are arguably reasonable assumptions to begin with, especially given that Republicans have earned a richly deserved reputation for blowing winnable races by picking bad nominees. We don’t even think it’s unreasonable to start with those as loose priors — in fact, our current forecasted outlook partly reflects this. The Republican Party rarely nominates “generic” candidates, and it has not given us much of a reason to believe that this will change in 2024.
But all of that would still only get Democrats to 49 seats, because Montana would still serve as a big stumbling block for them. Jon Tester won by just 3.6% in the D+7 blue wave of 2018 against Matt Rosendale, an exceptionally weak candidate. While Rosendale’s renomination could once again elevate the race to a tossup, Tester may still not be favored amid presidential-level turnout in a state that leaned 22 points to the nation’s right in 2020, especially as long as current polls hold and Biden and Trump remain tied nationally.
Moreover, with Rosendale’s fundraising currently looking anemic and with the congressman still not having announced a run, it is questionable as to whether he is currently still the favorite for the GOP nomination, especially with deep-pocketed NRSC recruit Tim Sheehy putting up a formidable challenge and taking the lead in recent primary polling. Tester’s odds of winning would likely go down significantly against Sheehy, making his re-election an uphill climb for Democrats. Given all of the factors mentioned above, we are shifting our rating for Montana from Tossup to Leans Republican.
With that, here is our updated Senate outlook.
It is also worth noting that Democrats also have very few genuine pickup opportunities — their best chance is perhaps with congressman Collin Allred taking on incumbent senator Ted Cruz, who barely won in 2018 against Beto O’Rourke. But Texas was still a Trump +6 state, and it leaned 10 points to the right of the nation in 2020. Cruz is probably a weak incumbent, and Allred will almost certainly not face any shortage of money, but it would be an immense stretch to imagine Allred actually winning under a tied national environment (or, really, under anything short of a 2020-esque presidential picture).
Early polling is historically not very predictive, and we are not saying that control of the Senate is guaranteed to flip. The chamber would still be clearly competitive, even under a tied national picture, and there are good reasons for Democrats to believe that their odds might only improve from here. The improving economic picture could give Joe Biden a boost as the incumbent president, especially if historical links between the economy and elections hold.
Moreover, if Donald Trump’s criminal trials lead to a conviction, it could meaningfully tank his standing against incumbent president Joe Biden in a general election. The resulting drag on downballot candidates, combined with some favorable candidate matchups, could boost Democratic odds and possibly even make them favorites for the chamber.
But that is a long list of factors that need to break favorably for Democrats, and we do not know that it is wise to assume that this is the default case. If it happens, we’ll revisit our assessment. Until then, however, our thoughts are simple: while both sides have a good chance at being in the majority come 2025, we think the Republicans are currently favored under today’s electoral picture, even with their history of nominating weak candidates. The race for control is competitive, but it is not a tossup.
I’m a computer scientist who has an interest in machine learning, politics, and electoral data. I’m a cofounder and partner at Split Ticket and make many kinds of election models. I graduated from UC Berkeley and work as a software & AI engineer. You can contact me at lakshya@splitticket.org