The partisan lean of this year's Senate map makes the GOP a favorite to win a majority. Despite Democrats outperforming the generic ballot, they must net win four GOP seats. This means that the Democrats have ground to make up in at least two deep red states among Alaska, Iowa, Ohio, and Texas, while also flipping Maine and North Carolina and holding Michigan. If the Democrats fall short of these targets, then the Republicans retain control. The odds are slightly in favor of the GOP majority, but given the historic unpopularity of the current Trump presidency, a Democratic upset in solid Republican territory is a real possiblity.
This year's Senate forecast is a continuation of the methodology as in 2024.
This model outcome differs from what most other forecasts and prediction markets are estimating, which is a much higher probability that the Democrats will flip the Senate. A few factors contribute to this phenomenon. One factor is that the model is making some assumptions about the fundamentals of deep red state Senate races in favor of Republicans, and raw polls that show Democrats overperforming in these races are being discounted in the model outcome. It is important to bear in mind that red state polling has had a history over recent years of polling errors that underestimated Republican votes. Another factor is how the model aggregates state-by-state results to produce the overall outcome, which can be unintuitive. The model believes that not all states necessarily demonstrate polling errors in the same way, and there are some regions that are anticorrelated, particularly the Midwest and the South, in a way that can skew the overall result depending on the battleground map. Democrats need to outrun expectations in more than one region to win 51 seats, while Republicans can hold onto at least 50 if they simply overperform in the Midwest. Meanwhile, Alaska and Maine remain wildcards that complicate the Democratic path to a majority. In 2024, this methodology boosted the probability of a Harris presidency by a few percentage points in the final outcome, while this year, it is boosting the probability of a GOP Senate hold by a few percentage points.
49 Democrats
Republicans 49
43
3
3
2
3
44
| 51 to win
Note that these numbers account for the fact that Sen. Angus King (I-ME) and Sen. Bernie Sanders (I-VT) are expected to continue to caucus with the Democrats.
We can put these state-by-state estimates together into an overall simulation of the whole Senate using the results of the 2020-NN-M model:
Party
Probability
Democrats
47.5%
Republicans
38.1%
50-50 split
14.4%
The median result is the Republicans winning 50-50.
The most likely result is the Democrats winning 51-49.
An 80% confidence interval ranges from Republicans winning 54-46 to Democrats winning 53-47.
For simplicity, Dan Osborn's independent candidacy in Nebraska is sorted into the "Democrat" category. Osborn has not declared which caucus to ally with if elected.
History
Date
Probability
Rated
Expected
Median
Most Likely
DEM
TIE
GOP
DEM
GOP
DEM
GOP
DEM
GOP
DEM
GOP
10/25
47.5%
14.4%
38.1%
49
49
49.9
50.1
50
50
51
49
10/19
48.5%
13.2%
38.3%
49
49
49.9
50.1
50
50
52
48
10/14
49.1%
11.0%
39.9%
48
50
50.1
49.9
50
50
53
47
10/08
40.2%
11.9%
47.9%
48
50
49.5
50.5
50
50
52
48
10/02
36.6%
11.8%
51.6%
47
50
49.3
50.7
49
51
48
52
09/26
42.1%
11.0%
46.9%
47
50
49.6
50.4
50
50
52
48
09/19
37.8%
11.6%
50.5%
47
51
49.2
50.8
49
51
52
48
09/06
41.6%
13.9%
44.5%
47
51
49.4
50.6
50
50
51
49
08/21
23.5%
27.4%
49.1%
47
51
49.3
50.7
50
50
50
50
Key Races
Alaska (Leans R). Incumbent Sen. Dan Sullivan (R) faces a stiff challenge from former Rep. Mary Peltola (D) in the Last Frontier. While Alaska is a solid Republican state and Sen. Sullivan has retained strong approval ratings, Peltola has ran a spirited and well-backed campaign and has been elected statewide before. Peltola is hoping that the anti-GOP environment in addition to her brand of retail politics is enough to carry a Democratic victory in a rural state, and polling has been strong for Peltola over the past few months. However, the fundamentals of taking out a popular incumbent in politically unfriendly territory is a tall order even in a wave election, and Sen. Sullivan remains a favorite to win.
Georgia (Likely D). Incumbent Sen. Jon Ossoff (D) is seeking reelection in a battleground state against Rep. Mike Collins (R). Despite having narrowly been elected in a runoff in 2021, Sen. Ossoff has built a brand over the years in the Peach State among the now-solid bench of Democratic voters based in the metro Atlanta area, and the broader partisan environment is lifting Ossoff. Rep. Collins's campaign has not quite taken off in the way that's typical of Republicans in Georgia, and that's leaving Sen. Ossoff as a favorite.
Iowa (Leans R). Rep. Ashley Hinson (R) is facing off against state Rep. Jack Turek (D) in a race to replace the retiring GOP incumbent Sen. Joni Ernst (R). Following President Obama's reelection in 2012, the collapse of support for Democrats among rural voters has effectively made the Hawkeye State out of reach for Democrats. This effect is particularly pronounced among traditionally Democratic voters in rural eastern Iowa. With inflation and high fuel prices hitting this rural state, polls have been tightening on Republicans this cycle. However, intermittently throughout the past decade, polling numbers have given Democrats false hope of winning statewide elections, and polling misses in Iowa have been particularly notable. This year, the partisan lean of Iowa is likely too large for a Democrat to overcome despite the anti-GOP mood, leaving Rep. Hinson the favorite to win.
Kansas (Likely R). Incumbent Sen. Roger Marshall (R) is running for reelection with a challenge from pastor Adam Hamilton (D) in a race that has been receiving a surprising amount of attention for a deep red state. Sen. Marshall has faced some tough headlines this fall over his residency and business practices from when Marshall was a private doctor, and the American heartland has been hit hard economically by inflation and energy prices. Kansas has not elected a Democratic Senator since 1932, but Kansas has seen disapproval of Republican governance over the past decade. Hamilton has also been running a local campaign appealing to moderate voters. Polls have indicated a surprisingly close race, but it is worth baring in mind that polling for this Senate seat has suffered from significant errors the past two cycles, and it should not be a surprise if this race does not end up being all that close. Given the fundamentals of this race, our best estimate is that this seat remains unlikely to actually flip to Democrats and Sen. Marshall is a heavy favorite for reelection.
Maine (Tossup). Incumbent Sen. Susan Collins (R) is running for reelection against former state Senate President Troy Jackson (D). Despite being consistently Democratic at the presidential level, upper New England states have had a streak of nominating independent-minded politicians from the other party, which has kept Sen. Collins in the Senate since her first election in 1996. Democrats have tried to ride out blue waves in the past to defeat Collins, including in 2008 and 2020, but none have succeeded, but they are trying again this year. Meanwhile, the Democrats have been in disarray this year following the mishap of nominating progressive oyster farmer Graham Platner (D), who was forced to withdraw from the race following allegations of sexual misconduct. Polls indicate a dead heat between Sen. Collins and Jackson, but it is not difficult to imagine Sen. Collins beating the polls to politically survive yet again.
Michigan (Leans D). Doctor Abdul Al-Sayed (D) is running against former Rep. Mike Rogers (R) to hold the seat of retiring incumbent Sen. Gary Peters (D). Rep. Rogers is seeking to run for the Senate again after having narrowly lost two years ago in Michigan's other seat by a fraction of a point. Meanwhile, Al-Sayed is trying to unify the Democrats following a divisive primary in which he narrowly defeated Rep. Haley Stevens (D), a political moderate. Al-Sayed is trying to pivot from his socialist political roots to win in a must-win race for the Democrats, and that has been a tall order in a purple state. The most recent polls indicate El-Sayed with a narrow lead.
Minnesota (Leans D). With the retirement of the Democratic incumbent Sen. Tina Smith, Minnesota's Senate race features Lt. Gov. Peggy Flanagan (D) and journalist Michele Tafoya (R). Despite it being a light blue state in a blue wave year, this race has featured surprisingly close polls. One explanation for this is that Minnesota is seeing discontent with Democratic government at the statewide level over the past few years, while another is that Lt. Gov. Flanagan has been running an unabashedly far-left campaign. That being said, it is still expected that the national environment and Minnesota's partisan lean is going to carry Flanagan over the top.
New Hampshire (Likely D). Rep. Chris Pappas (D) and former Sen. John Sununu (R) are running to fill the seat of retiring incumbent Sen. Jeanne Shaheen (D). Sen. Shaheen first won this seat in 2008 by unseating then-Sen. Sununu, and Sununu is attempting a comeback. While New Hampshire is a state with local politics and swing voters, this remains a blue wave environment in a light blue state. Republican politicians from the Sununu family have overperformed over the past several decades in New Hampshire, but this it might not be enough to carry John Sununu to victory this year, and this seat is expected to remain in the Democratic column.
North Carolina (Likely D). Former Gov. Roy Cooper (D) is attempting to flip a GOP seat following the retirement of incumbent Sen. Thom Tillis (R). Gov. Cooper's challenger, former RNC chair Michael Whatley (R), has run an underwhelming campaign in a state that has been historically favorable to Republicans. Cooper retains statewide popularity following his two terms as governor and has had a history of winning despite President Trump carrying the Tar Heel State at the top of the ticket. Gov. Cooper is the clear favorite in the final stretch in the race, and this seat is the most likely to change hands this cycle.
Ohio (Leans D). Appointed incumbent Sen. Jon Husted (R) is running in a special election following former Sen. J. D. Vance's (R) election to the Vice Presidency. Meanwhile, former Sen. Sherrod Brown (D) is attempting a political comeback in a state that has become increasingly unfavorable to Democrats. In each of his previous elections, Brown rode a blue wave in a once-purple state with a strong base of union voters loyal to Democrats, but that ended with his reelection defeat in 2024 against now-Sen. Bernie Moreno (R). Brown is perhaps the only Democrat remaining in Ohio capable of winning statewide, and he is making use of the political environment to reclaim a seat. Ohio is one of several states on the Democrat's path to a majority. Polls here have indicated a small but consistent lead for Brown, but there are still strong fundamentals pulling for Sen. Husted.
Texas (Tossup). State Attorney General Ken Paxton (R) won an endorsement from President Trump to defeat longtime incumbent Sen. John Cornyn (R) in a primary. Paxton has a history of political scandals and has been running as a right-wing hardliner, which Democratic state Rep. James Talarico is hoping to utilize to flip deep-red Texas blue. Winning Texas has been much of a white whale over the past decade for national Democrats, but they're hoping that this time the national attention and fundraising leads to a different outcome. Current polling indicates a small but consistent lead for Talarico, which perhaps suggests that the Democrats' history in Texas might not just be repeating itself this year. Particularly, polling nationwide has shown Hispanic voters particularly souring on President Trump and Republicans due to the state of the economy, and that is having a significant effect in Texas. Flipping Texas remains no small order for Democrats despite these factors, and this race remains highly uncertain.
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