---
title: Scoring the 2026 U.S. Midterm Forecast: Direction, Magnitude and Lessons for Method
author: Dr. Tong Yin
source_name: InsightBridge Global Intelligence
source_url: https://intelligence.insightbridge.global/articles/us-midterms-2026-forecast-scorecard
published_at: 2026-11-05T06:09:28.848082+00:00
category: 综合
lang: en
license_note: 引用本文必须保留上述作者署名与原始链接 (Attribution required when citing.)
---
Scorecard · U.S. midterms 2026 · 5 November 2026 · Preliminary assessment; data as of 4–5 November, counting not complete

*Scoring the final edition of “The 2026 U.S. Midterms and the Road to 2028” against the outcome, under scoring rules registered before the vote.*

Dr. Tong Yin, Chief Research Officer, InsightBridge Global and InsightBridge Global Lab.

**Independence statement:** This is an independent, third-party analysis. It takes no political, partisan, ideological or national position. It assesses the accuracy of a forecast, not the merits of any party or candidate.

**Download the scorecard (English PDF)** · **下载中文版 PDF**

## 1. Why publish a scorecard

This study published “The 2026 U.S. Midterms and the Road to 2028” on 14 October 2026 and revised it three times, on 23, 24 and 31 October. The final edition appeared three days before the vote. The House district model was frozen on 30 October and the state-level Senate model was registered on 31 October. Both are held in a timestamped version-controlled repository, together with scoring rules written before the election.

A forecast is only as useful as its willingness to be checked. Voting ended on 3 November. Some seats are still being counted, but the available data are sufficient for a preliminary assessment of the main judgments. This scorecard applies the pre-registered scoring rules, compares each forecast with the outcome, and records what was right and what was wrong.

## 2. Summary

  | **Item**  | **Forecast (final edition, 31 Oct)**  | **Preliminary outcome**  | **Grade**

  | House control  | Democratic majority, about 90%  | Democratic majority  | Strong

  | Senate control  | Democratic control, about 65%  | Democratic control  | Strong

  | Combined outcome  | Democratic sweep, about 61%, most likely scenario  | Democratic sweep  | Strong

  | Main drivers  | Energy-driven cost of living; low presidential approval  | Confirmed by exit polls  | Strong

  | Senate seats and state calls  | Model median 52; 10 of 12 decided states called correctly  | 54 seats secured, leading in two more  | Good

  | House seats  | Author’s central range 222–238  | Preliminary estimate about 255–258  | Weak

  | Confidence of probabilities  | Below prediction markets in every edition  | Outcome fell on the more confident side  | Fair

  | Transparency of process  | Models and scoring rules registered before the vote  | Review follows the original rules  | Strong

In one sentence: every directional call was right and the causal reading held, but the size of the result was underestimated, most clearly in the House. The sources of that underestimate can be identified, and Section 5 sets them out.

## 3. Forecast against outcome

### 3.1 House

As of early 5 November, the Associated Press counted 237 Democratic seats, with 51 still to be called ([AP](https://apnews.com/projects/elections-2026/us-house-results)). The NBC News Decision Desk estimates that Democrats will win at least 258 seats ([NBC News](https://nbcnews.com/politics/2026-elections/house-results)), and the House Democratic leader said he expects at least 255 ([CBS News](https://www.cbsnews.com/live-updates/house-election-results-2026/)). This scorecard uses 255–258 as the preliminary outcome range.

House ranges

  | **Forecast**  | **Median**  | **Range**  | **P(majority)**  | **Seat error (median minus 255–258)**  | **Range covers outcome**

  | Author judgment  | about 230  | 222–238  | about 90%  | −25 to −28  | No

  | R1 main  | 239  | 212–269  | 85.5%  | −16 to −19  | Yes

  | R2 poll discount  | 229  | 199–255  | 71.0%  | −26 to −29  | Borderline

  | R3 Cook ratings  | 228  | 220–236  | 95.9%  | −27 to −30  | No

  | R4 two-party  | 240  | 213–271  | 86.4%  | −15 to −18  | Yes

  | R5 historical calibration  | 236  | 218–253  | 90.7%  | −19 to −22  | No

Three observations:

1. **Control was called correctly.** Every scenario treated a Democratic majority as the likely outcome.
1. **The author’s range was too low.** Its upper bound was 238 seats. Democrats already hold 237 called seats with 51 outstanding, so the final figure will clearly exceed the range.
1. **The main model’s ranges covered the outcome, but its median was also low.** The 80% ranges of R1 and R4 cover 255–258 seats; the narrower R3 and R5 ranges do not. The two scenarios that adjusted polls downward for Democrats (R2 and R5) had larger errors than the unadjusted scenarios.

### 3.2 National vote

Pre-election averages of the generic congressional ballot put Democrats ahead by roughly 8 to 9 points. Silver Bulletin’s average, frozen on Election Day, was D+8.8 ([Silver Bulletin](https://www.natesilver.net/feed)), and this study’s model input was D+8.73. The New York Times, using voter-file data and precinct results, estimates the Democratic margin in the national House vote at about 13 points ([New York Times](https://www.nytimes.com/interactive/2026/11/03/us/elections/results-house.html)). If that estimate holds, the polls understated Democrats by about 4 points. That is the main reason the seat forecast was too low.

### 3.3 Senate

Democrats have secured 54 seats. Alaska and Mississippi are uncalled, with the Democratic candidates narrowly ahead in both ([AP](https://www.usnews.com/news/politics/articles/2026-11-04/which-senate-governors-races-are-still-uncalled-by-the-associated-press)). Democrats flipped seven Republican-held seats: Iowa, Kansas, Maine, North Carolina, Ohio, South Carolina and Texas ([CNN](https://edition.cnn.com/2026/11/04/politics/live-news/midterm-election-congress?t=1793783891378&post-id=cmw1uw4mr00013b6vq64gp2fa)). Republicans held Nebraska ([AP](https://apnews.com/projects/elections-2026/united-states-results/nebraska-us-senate-results/)) and Montana ([AP](https://apnews.com/projects/elections-2026/montana-us-senate-results/)).

  | **Forecast**  | **Median**  | **Range**  | **P(Democratic control)**  | **If 54 seats**  | **If 56 seats**

  | S1 main  | 52  | 48–55  | 68.8%  | Covered, error −2  | Not covered, error −4

  | S2 historically calibrated  | 51  | 46–54  | 51.1%  | Covered, error −3  | Not covered

  | S4 wider national error  | 52  | 46–56  | 63.7%  | Covered  | Covered

  | Author judgment  | —  | —  | about 65%  | Direction correct  | Direction correct

The report said Democrats needed to win four of seven Republican-held battlegrounds while holding Michigan, Georgia and New Hampshire. They won six of the seven, with Alaska still counting. They also won South Carolina, which was outside the seven, and held all three defended seats.

**State calls.** Of the 12 decided states for which the model gave a probability, the S1 main scenario called 10 correctly, with a Brier score of about 0.11. The two misses were Iowa (Democratic probability 47%) and South Carolina (35%); both underestimated Democrats. The model gave the independent challenger in Nebraska 28%, and the Republican won, so that call was correct. Mississippi was not on the model’s list of competitive states, which was an omission.

State polls versus results

In 10 of the 11 states shown, final poll averages understated the Democratic side, by about 5 points on average. The range ran from 0.7 points in Ohio to 9.5 points in Texas. Nebraska was the one exception: the Republican incumbent outperformed his polls by about 5 points. The challenger there was an independent rather than a Democrat, which suggests that polls of independent challengers may carry a different error structure. State results are preliminary counts of 4 November ([RealClearPolitics data as compiled](https://legalinsurrection.com/2026/11/republicans-wake-up-to-an-electoral-bloodbath/); Texas from [NBC News](https://www.nbcnews.com/politics/2026-elections/texas-senate-results)).

### 3.4 Main drivers

The report judged energy-driven living costs to be the main economic channel and low presidential approval to be the central feature of the national environment. CBS News exit polls found that 89% of voters called the cost of living a major or crucial factor, and presidential approval stood at 38% ([CBS News](https://www.cbsnews.com/live-updates/house-election-results-2026/)). After the vote, the president said it was “largely true” that the Iran war contributed to Republican losses ([CNN](https://edition.cnn.com/2026/11/04/politics/live-news/midterm-election-congress?post-id=cmw276q0200003b6xb6q42y1x)). These data support the report’s account of how energy prices and the Iran conflict fed through to voters.

## 4. Probability scores against markets and outside models

The Brier score measures the distance between a probability and the outcome. It runs from 0 to 1, and lower is better.

Senate Brier scores

  | **Judgment**  | **Editions of this report**  | **Comparators**

  | House control  | 14 Oct: 88% (0.014); 31 Oct: 90% (0.010)  | Kalshi 93.9% (0.004)

  | Senate control  | 14 Oct: 56% (0.194); 23 Oct: 62% (0.144); 31 Oct: 65% (0.122)  | Kalshi 70% (0.090); Polymarket 71% (0.084); Silver FLIPR 77.7% (0.050); DDHQ 62% (0.144)

  | Democratic sweep  | 14 Oct: 54% (0.212); 31 Oct: 61% (0.152)  | Markets in mid-October: 60–62%

Two conclusions follow:

1. **Each revision moved toward the outcome, and the score improved each time.** The Senate Brier score fell from 0.194 to 0.144 and then to 0.122, so the revisions responded correctly to new information.
1. **Every edition was more cautious than the markets.** The report deliberately set its Senate probability below the market price, on the grounds that state polling errors may be correlated and that markets may chase momentum. The reasoning is sound in itself, but the outcome fell on the more confident side, so the final edition scored worse than the markets and some outside models.

One election provides one test. A 65% call that comes true is consistent with good calibration but does not prove it. Formal conclusions rest on backtests over 2006–2024 and on the record accumulated across future cycles.

## 5. Where the errors came from

**First, the assumed direction of polling error was the opposite of what occurred.** The report treated a repeat Republican over-performance of about 3 points as the leading risk, based on the 2024 swing-state experience. Scenario R5 shifted the national environment about 1 point toward Republicans, based on the 2006–2024 average bias. This time the polls understated Democrats, by about 4 points. The historical average is useful context, but its sign is not stable from cycle to cycle and should not be applied as a one-directional correction.

**Second, market prices were discounted in one direction.** The report’s Senate probability sat below the market in every edition. The correlated-error argument is symmetric: it can leave a party short of its polls or carry it well beyond them. This time it was the latter.

**Third, signals pointing the other way did not enter the central estimate.** The report cited a Fox News poll in Maine showing Democratic enthusiasm at 79% against Republican enthusiasm at 61%, with the Democratic candidate leading by 40 points among those who had already voted. Enthusiasm and turnout signals of this kind pointed to Democrats beating their polls, but they were used only descriptively and did not enter the seat or probability calculations.

**Fourth, the author’s range was narrower than the model’s.** The author’s central range of 222–238 seats was only 16 seats wide and leaned on Cook ratings and market seat expectations; the R1 model range was 212–269. A narrow range is more easily breached when the national vote moves substantially.

**Fifth, the list of competitive states was incomplete.** Mississippi ended as a contest decided by a few dozen votes, but it was not on the Senate model’s list.

## 6. What went right

- **Every directional call was correct:** the House, the Senate and the combined outcome.
- **The causal reading held:** living costs, energy prices and presidential approval were confirmed as the main drivers.
- **The Senate path was correctly identified:** the decisive states, the seats that had to be held and the four-of-seven threshold all matched the outcome.
- **Revisions moved the right way:** each revision moved toward the outcome, and the probability score improved each time.
- **The process was testable:** the models, data hashes and scoring rules were registered before the vote, so this review follows criteria fixed in advance rather than measures chosen after the fact.

## 7. Improvements for 2028

1. Treat polling error symmetrically: model its direction as part of the uncertainty rather than applying a one-way correction from the historical mean.
1. Bring enthusiasm, early-vote composition and participation by low-propensity voters into the model as formal inputs, and backtest their incremental value.
1. Widen the author’s seat range to at least match the model’s; seat conversion can become non-linear when the national environment shifts sharply.
1. Apply no preset directional discount to prediction markets. Any departure from the market should rest on a quantified reason and be scored separately afterwards.
1. Widen the Senate screen to include every state with a polling gap within 10 points.
1. Continue the original, state-stratified sampling plan for 2028 to reduce reliance on public polls.

## 8. Data still to be confirmed

This is a preliminary assessment. An updated edition will follow once these data are settled:

- Mississippi Senate: provisional ballots must be resolved by 10 November ([AP](https://www.usnews.com/news/politics/articles/2026-11-04/which-senate-governors-races-are-still-uncalled-by-the-associated-press)).
- Alaska Senate: all ballots must be counted by 18 November, followed by a ranked-choice tabulation if needed ([New York Times](https://www.nytimes.com/2026/11/04/us/mississippi-alaska-senate-recount-provisional-ballots.html)).
- About 50 House seats remain uncalled; final seat totals will follow the figures of the Clerk of the House.
- The national House vote margin will follow state certifications.
- The district-level Brier score requires results from all 435 districts.

## 9. Conclusion

On the questions that mattered most, the forecast was right: Democrats won control of both chambers, and the main drivers were living costs and energy prices. Where it fell short was magnitude. Assumptions about the direction of polling error, a discount to market prices and a narrow author range led to a systematic underestimate of the size of the result, most visibly in the House.

Recording these errors openly matters as much as recording the correct calls. They give the 2028 research design a clear agenda for improvement. An updated scorecard will be published once counting is complete.

## References

1. Tong Yin, “The 2026 U.S. Midterms and the Road to 2028: Evidence, Scenarios and Implications for the Economic Outlook,” InsightBridge Global Intelligence, first edition 14 October 2026, final edition 31 October 2026. [https://intelligence.insightbridge.global/articles/us-midterms-2026-road-to-2028](https://intelligence.insightbridge.global/articles/us-midterms-2026-road-to-2028)
1. Associated Press, 2026 U.S. House results. [https://apnews.com/projects/elections-2026/us-house-results](https://apnews.com/projects/elections-2026/us-house-results)
1. NBC News, 2026 House election results. [https://nbcnews.com/politics/2026-elections/house-results](https://nbcnews.com/politics/2026-elections/house-results)
1. CBS News, 2026 House midterm election results (live updates). [https://www.cbsnews.com/live-updates/house-election-results-2026/](https://www.cbsnews.com/live-updates/house-election-results-2026/)
1. New York Times, U.S. House election results. [https://www.nytimes.com/interactive/2026/11/03/us/elections/results-house.html](https://www.nytimes.com/interactive/2026/11/03/us/elections/results-house.html)
1. Silver Bulletin, generic congressional ballot average. [https://www.natesilver.net/feed](https://www.natesilver.net/feed)
1. Associated Press, “Which Senate, governors races are still uncalled.” [https://www.usnews.com/news/politics/articles/2026-11-04/which-senate-governors-races-are-still-uncalled-by-the-associated-press](https://www.usnews.com/news/politics/articles/2026-11-04/which-senate-governors-races-are-still-uncalled-by-the-associated-press)
1. CNN, midterm election live updates. [https://edition.cnn.com/2026/11/04/politics/live-news/midterm-election-congress?t=1793783891378\&post-id=cmw1uw4mr00013b6vq64gp2fa](https://edition.cnn.com/2026/11/04/politics/live-news/midterm-election-congress?t=1793783891378\&post-id=cmw1uw4mr00013b6vq64gp2fa)
1. CNN, midterm election live updates (post-election remarks). [https://edition.cnn.com/2026/11/04/politics/live-news/midterm-election-congress?post-id=cmw276q0200003b6xb6q42y1x](https://edition.cnn.com/2026/11/04/politics/live-news/midterm-election-congress?post-id=cmw276q0200003b6xb6q42y1x)
1. Associated Press, Nebraska U.S. Senate results. [https://apnews.com/projects/elections-2026/united-states-results/nebraska-us-senate-results/](https://apnews.com/projects/elections-2026/united-states-results/nebraska-us-senate-results/)
1. Associated Press, Montana U.S. Senate results. [https://apnews.com/projects/elections-2026/montana-us-senate-results/](https://apnews.com/projects/elections-2026/montana-us-senate-results/)
1. NBC News, Texas Senate results. [https://www.nbcnews.com/politics/2026-elections/texas-senate-results](https://www.nbcnews.com/politics/2026-elections/texas-senate-results)
1. RealClearPolitics preliminary results, as compiled by Legal Insurrection. [https://legalinsurrection.com/2026/11/republicans-wake-up-to-an-electoral-bloodbath/](https://legalinsurrection.com/2026/11/republicans-wake-up-to-an-electoral-bloodbath/)
1. New York Times, “Alaska and Mississippi Senate Races: What We Know.” [https://www.nytimes.com/2026/11/04/us/mississippi-alaska-senate-recount-provisional-ballots.html](https://www.nytimes.com/2026/11/04/us/mississippi-alaska-senate-recount-provisional-ballots.html)

**Note:** The House v5 model was frozen at 18:00 CT on 30 October 2026 (code commit 625aebc7; registration file SHA-256 cba93d3e…a051c). The R5 scenario addendum and the Senate model were registered on 31 October, and the turnout-coding addendum on 1 November. The files are available for review on request.