Our 2018 Senate forecast shows the Democrats having a better night than many other competing forecasts, with Democrats having a roughly 1 in 4 chance of winning the Senate and keeping the Senate at 51-49 Republican on average.
Without getting into the details of the model, the main reason I am slightly more optimistic about the Senate for Democrats than others boils down to two reasons. First, Democrats have a sizable lead in the generic national popular vote, by roughly 8 to 9 points. Second, history shows that it’s incredibly difficult to defeat incumbent senators from the opposing party to the President in a midterm election, which bodes well for the numerous Democratic incumbents up for re-election in states that Trump won. That doesn’t mean that they will all survive, just that they probably have a better chance of winning than other prognosticators are giving them.
Unfortunately, due to a heavy school course-load, I won’t be able to publish the methodology of my model until after election day. But the full results of the model are still posted below. Happy election day!
Overall Senate Forecast
| Category | Democratic | Republican |
|---|---|---|
| Win Senate Majority? | 26.7% | 73.3% |
State-Level Forecasts
| State | Dem Win% | Rep Win% | Dem Vote% | Rep Vote% | Race Rating |
|---|---|---|---|---|---|
| California | 100.0% | 0.0% | 65.0% | 35.0% | Safe D |
| Delaware | 100.0% | 0.0% | 65.0% | 35.0% | Safe D |
| Hawaii | 100.0% | 0.0% | 65.0% | 35.0% | Safe D |
| Maryland | 100.0% | 0.0% | 65.0% | 35.0% | Safe D |
| Massachusetts | 100.0% | 0.0% | 65.0% | 35.0% | Safe D |
| New Mexico | 100.0% | 0.0% | 65.0% | 35.0% | Safe D |
| New York | 100.0% | 0.0% | 65.0% | 35.0% | Safe D |
| Rhode Island | 100.0% | 0.0% | 65.0% | 35.0% | Safe D |
| Vermont | 100.0% | 0.0% | 65.0% | 35.0% | Safe D |
| Washington | 100.0% | 0.0% | 65.0% | 35.0% | Safe D |
| Minnesota | 99.9% | 0.1% | 62.5% | 37.5% | Safe D |
| Maine | 99.8% | 0.2% | 59.8% | 40.2% | Safe D |
| Connecticut | 99.8% | 0.2% | 58.5% | 41.5% | Safe D |
| Virginia | 99.2% | 0.8% | 56.7% | 43.3% | Safe D |
| Michigan | 98.5% | 1.5% | 58.2% | 41.8% | Safe D |
| New Jersey | 98.4% | 1.6% | 58.0% | 42.0% | Safe D |
| Pennsylvania | 97.6% | 2.4% | 55.5% | 44.5% | Safe D |
| Wisconsin | 95.1% | 4.9% | 55.1% | 44.9% | Safe D |
| Minnesota Special | 95.1% | 4.9% | 54.7% | 45.3% | Safe D |
| West Virginia | 93.3% | 6.7% | 57.0% | 43.0% | Solid D |
| Ohio | 91.5% | 8.5% | 54.6% | 45.4% | Solid D |
| Montana | 84.5% | 15.5% | 53.2% | 46.8% | Likely D |
| Florida | 80.0% | 20.0% | 52.9% | 47.1% | Likely D |
| Indiana | 70.5% | 29.5% | 51.8% | 48.2% | Lean D |
| Nevada | 67.4% | 32.6% | 51.3% | 48.7% | Lean D |
| Missouri | 63.0% | 37.0% | 51.0% | 49.0% | Tilt D |
| Arizona | 62.2% | 37.8% | 51.0% | 49.0% | Tilt D |
| North Dakota | 35.0% | 65.0% | 48.4% | 51.6% | Lean R |
| Tennessee | 23.7% | 76.3% | 47.7% | 52.3% | Likely R |
| Texas | 23.5% | 76.5% | 47.7% | 52.3% | Likely R |
| Mississippi Special | 7.8% | 92.2% | 44.6% | 55.4% | Solid R |
| Nebraska | 5.6% | 94.4% | 44.8% | 55.2% | Solid R |
| Mississippi | 1.5% | 98.5% | 43.3% | 56.7% | Safe R |
| Utah | 0.6% | 99.5% | 35.6% | 64.4% | Safe R |
| Wyoming | 0.0% | 100.0% | 25.0% | 75.0% | Safe R |
Additional Senate Predictions
| Category | Democratic Seats | Republican Seats | Category | Yes | No |
|---|---|---|---|---|---|
| Average Seats | 48.9 | 51.1 | Dems Lose Incumbent? | 84.3% | 15.7% |
| Median Seats | 49 | 51 | Reps Lose Incumbent? | 72.3% | 27.7% |
| Mode Seats | 49 | 51 | Dems Pick Up Seats? | 42.7% | 57.3% |
| 95th Percentile | 53 | 47 | Reps Pick Up Seats? | 40.9% | 59.1% |
| 75th Percentile | 51 | 49 | Max Democratic Seats | 57 | 43 |
| 25th Percentile | 47 | 53 | Min Democratic Seats | 38 | 62 |
| 5th Percentile | 45 | 55 | Projected Generic Ballot: | 54.7% | 45.3% |
Range of Outcomes
| Democratic Seats | Probability |
|---|---|
| 55+ | 0.4% |
| 54 | 1.4% |
| 53 | 4.0% |
| 52 | 8.2% |
| 51 | 12.8% |
| 50 | 16.0% |
| 49 | 16.3% |
| 48 | 14.1% |
| 47 | 10.6% |
| 46 | 7.4% |
| 45 | 4.5% |
| 44 | 2.4% |
| 43 | 1.1% |
| 42 | 0.5% |
| 41 | 0.2% |
| 40- | 0.1% |

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