Background
The equation used to predict the Democratic share of the two-party House vote for 2026 is equation 3a in Table 2 inPresidential and Congressional Vote-Share Equations: November 2022 Update.
The following discussion assumes that the paper,
Presidential and Congressional Vote-Share Equations, American Journal of Political Science, January 2009, 55-72
has been read. You can compute your own vote prediction using your own assumptions about the economy by clicking:
Compute your own prediction for 2026.
Current and Past Predictions:
Pcc Zcc Vcc
February 20, 2026 3.49 2 50.68
December 23, 2025 2.45 3 49.16
Executive Summary
The above shows that the current prediction of the Democratic share of the two-party House vote in 2026 (Vcc) is 50.68 percent. This is an increase from 49.16 in December. The prediction of inflation (Pcc) is now higher, and there is one fewer predicted strong growth quarters (Zcc). These two changes help the Democrats. The election is predicted to be close. The standard error is about 3 percentage points, so the election is too close to call given the economic values. It will be decided by non economic factors that are not in the equation. The following is the detailed discussion.Economic Assumptions and Vote Prediction: February 20, 2026
The two economic variables in the equation, using the notation in Table 1 in the above November 2022 update, arePcc = the growth rate of the GDP deflator in the first 7 quarters of the second Trump administration, 2025:1-2026:3, at an annual rate,
and
Zcc = 15/7 times the number of quarters in the first 7 quarters of the second Trump administration in which the growth rate of real per capita GDP is greater than 3.2 percent at an annual rate.
As of this writing data are available for the first four quarters of the second Trump administration. For these four quarters the growth rate of the GDP deflator is 3.36 percent at an annual rate and there are 2 strong growth quarters, 2025.2 and 2025.3.
Forecasts of the U.S. economy for 2026.1--2029.4 using the US model are on this website--Economic Forecasts. There are no more strong growth quarters forecast, and inflation is predicted to be about 3.6 percent at an annual rate. Using the actual values for 2025.1--2025.4 and the forecast values for 2026.1--2026.3, the value of Pcc is 3.49 and the value of Zcc is 4.286.
The prediction also needs the values of the two-party Democratic vote share in the 2024 election for the president, Vp-2, and for the House, Vc-2. The value of the former is 49.25 percent (Harris), and the value of the latter is 48.68 (House Democrats).
The following gives a breakdown of the prediction using the notation in Table 1 and the coefficient estimates in equation 3a in Table 2 of the update.
49.04 Constant term
3.36 Coefficient estimate of I times -1 (the Republican party in power in
the White House).
-0.92 0.695*(Vc-2 - 50) = 0.695*(48.68 - 50). House incumbency effect.
0.17 -0.228*(Vp-2 - 50) = -0.228*(49.25 - 50). Estimated effect from the
size of the presidential vote share in the last election
(balance effect).
51.65 TOTAL so far
1.29 -0.370*Pcc*I. Assuming Pcc = 3.49. Inflation effect.
-2.26 0.528*Zcc*I. Assuming 2 strong growth quarters,
where Zcc = (15/7)*2 = 4.286.
50.68 PREDICTED VOTE SHARE FOR DEMOCRATS
The predicted two-party vote share for the House Democrats is 50.68 percent.
This is predicted vote share, not seats.
The prediction shows that the Democrats lose more from output growth than they gain from inflation (-2.26 versus 1.29). The Republicans benefit from the fact that the second are third quarters of 2025 are strong growth quarters.
The Democrats are hurt somewhat by the House incumbency effect (-0.92). They are helped slightly by the balance effect, but only slightly (0.17). The main positive effect for the Democrats is the estimated 3.36 gain from the fact that the Republicans are the party in power in the White House. The estimated constant term is slightly in the Republican's favor (49.04).
This prediction will change in the next three quarters as more is known about the economy in 2026. You can compute your own vote prediction using your own assumptions about the economy by clicking the above link.