Alert
The House prediction below is compared to predictions from betting markets at this link: Comparison. This link is due to Mae Chew.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
October 29, 2026 3.36 4.286 50.63
July 31, 2026 4.05 4.286 50.89
April 30, 2026 3.43 4.286 50.66
February 20, 2026 3.49 4.286 50.68
December 23, 2025 2.45 4.286 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 50.63 percent. This is slightly below the prediction in July because inflation is lower. The election is predicted to be close. The standard error is 2.39 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 Values: October 29, 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.
At the time of this writing preliminary data are available for all seven quarters of the second Trump administration. (NIPA data released October 29, 2026.) Pcc is 3.36 and Zcc 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
1.24 -0.370*Pcc*I. Assuming Pcc = 3.36. Inflation effect.
-2.26 0.528*Zcc*I. Assuming 2 strong growth quarters,
where Zcc = (15/7)*2 = 4.286.
50.63 PREDICTED VOTE SHARE FOR DEMOCRATS
The predicted two-party vote share for the House Democrats is 50.63 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 1.24). 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).