Democrats are overwhelming favorites to win the House of Representatives, and they are slightly ahead in the race for the Senate. As their lead in the generic congressional ballot grows and double-digit-lead polls begin to trickle in, I asked myself: how bad can this get for Republicans?
In midterm elections, pundits throw around keywords to describe the scope of a party’s victory: trickle, wave, tsunami.
Blue Trickle, Wave, or Tsunami?
These words don’t have any clear definitions, and people may disagree with my judgment, but here’s my understanding. A trickle is a modest, but often underwhelming victory. Think about the 2022 midterms, when Republicans narrowly won the House and failed to retake the Senate despite higher expectations (Generic Ballot of R+2.5). A wave year needs at least a solid victory in the House and a decent Senate performance. 2018 is the most recent example of a strong wave year, when Democrats won 235 House seats with a generic ballot of D+8.6. They lost two Senate seats, but mostly because a difficult map had them defending seats ruby-red in South Dakota and Missouri. To win these kinds of impossible seats, both in the House and Senate, you’d need a tsunami. For that, I would argue, you’d need to win both chambers and at least 235-240 House seats.
Even in the face of Republican Gerrymandering, Democrats are very close to that target.
E-mail readers can open this post in the web for better visuals.
The chart above represents the Election for the House of Representatives. Each dot represents a district, and the x-axis shows a neutral national environment. Meaning, if 2026’s congressional vote were to be a tie, Democrats would win all seats to the right of 0, and Republicans would win all seats to the left of zero. In that scenario, Republicans would win the House, because they gerrymandered more states than Democrats.
You can easily spot the effect of Gerrymandering in the chart. Gerrymandering from both sides removed competitive districts and increased the number of districts with a partisan lean of 15-25 points, creating a gerrymandering valley around the zero mark. But not only districts with competitive partisan leanings move to that “mountain” area on the chart. Districts that were considered extremely safe (partisan lean of +60 for either party) move there as well, as they take in and dilute votes of the opposing party.
2026 won’t be a neutral environment. The generic ballot is currently forecasted at D+9.6 points, flipping many seats to the Democrats. Today’s forecast has them winning 239 seats. That’s tsunami territory. During the summer, their generic ballot lead only pointed to modest gains, largely because each two-point step netted only a few seats (dots on our chart). But as they approach double digits, the Republican gerrymandering mountain comes into view.
To show this, I ran different generic ballot results through my model. I chose a range from D+6 to D+12, which roughly covers the standard margin of error for single points.
Going from D+6 to D+7 and from D+7 to D+8 only netted Democrats three additional seats each time. However, going from D+10 to D+11 would net Democrats a total of seven seats.1
In that scenario, Democrats would sweep Colorado and pick up seats like Florida’s 27th, causing a Republican gerrymander to backfire. If you are interested in a district-level analysis, Johnny from PlusMinus4 published a great district-level analysis last night about where the Democratic Tsunami could hit Republicans.
A double-digit result would not only mean a tsunami election in the House and likely a comfortable win in the Senate, but it would also mean a historic loss for President Donald Trump.
Democrats Might Make History in Nov. 3rd
As Nate Silver pointed out, wave elections for the out-of-power party are the rule in midterm elections. Tsunami elections, however, are very rare.
With the current forecast of D+9.6, Democrats would set the record for the highest congressional ballot victory in a midterm in the 21st century, outdoing their record from 2018.
If the NYT poll of D+11 turns out to be right on the money, it would be the best result of the 21st century, period. Even landing ahead of Democrats’ 2008 landslide, when Barack Obama was elected President and Democrats won 257 seats in the House, together with a Supermajority in the Senate.2
It would be the largest congressional ballot victory since 1982, when Democrats won by 11.8 points.
Do you think Democrats can reach double digits?
There might be some discrepancy when comparing it to the dotted chart, because the GB line is slightly off its true value. Also, the dotted chart was made with a D+9.7 forecast, today’s forecast stands at D+9.6 (this only affects Wisconsin’s 1st district).
Such a Senate majority is highly unlikely in today’s polarized political environment.