What’s at Play in the 2018 Senate Races

Our Latest 2018 Senate Prediction

Updated Dec. 13
43 Democrats
48 Republicans
9 Toss-Ups

After Donald Trump’s election, Democrats had basically given up on winning the Senate in 2018. Of the 34 senators up for election, 26 are Democrats (or caucus with Democrats), and ten of those are from states that Trump won, including five from states he won by at least 18 points: Joe Donnelly (Indiana), Claire McCaskill (Missouri), Jon Tester (Montana), Heidi Heitkamp (North Dakota), and Joe Manchin (West Virginia). And since Minnesota senator Al Franken resigned after allegations of groping by several women, the party will also need to defend a seat they hadn’t anticipated. Franken’s seat has been filled by Lieutenant Governor Tina Smith, a Democrat who will run in 2018, and the Cook Political Report has rated the seat a toss-up.

However, Doug Jones’s unexpected win in the Alabama special election upended expectations, giving the party a much wider path to the Senate, and significant momentum. Some analysts say that Trump’s abysmal 48 percent approval rating in Alabama was (along with the epically terrible candidate the Republicans had in Roy Moore) a significant factor, and he has comparable numbers in a lot of other states as well. Democrats still have to do everything perfectly to take back the Senate next year, which entails successfully defending all vulnerable blue seats and then winning two more. The indicators, though, suggest for the first time that it’s plausible. Dean Heller’s approval rating has tanked in Nevada, and Tennessee’s Bob Corker and Arizona’s Jeff Flake have announced their retirements.

Jump to the list of competitive seats.

To get a better sense of how the next election cycle may play out, we’ve pulled together analysis of the most competitive seats, relying on data from election-analysis sites as well as the latest polling, approval ratings, and party target lists. As of mid-December, we’ve determined 13 competitive races.

The Current Senate

There are currently 51 Republicans and 49 Democrats in the Senate, which means Democrats need at least two more seats to retake the chamber. Of the 13 most competitive races, ten are held by Democrats and three by Republicans.

If Trump’s low approval rating costs Republicans

It’s harder to predict the impact that Trump’s low approval rating might have on Senate races (though there is heavy historical evidence that it’s bound to cost him in the House). We figured out how the Senate would look if Republicans lost reelection in states where Trump has a lower-than-50 percent approval rating — Nevada and Arizona (where Republicans are already in trouble) and Nebraska (a long shot).

If incumbents with an approval rating under 50 percent lose

There are a whopping 18 senators with approval ratings under 50 percent, paving the way for challengers (or, in the case of retirements, an opening for the other party).

But larger trends alone can’t predict individual races, where (of course) the actual candidates themselves affect the results. Below, we go deep on each competitive race, looking at a range of factors that will influence the election, including fundraising ability, statewide presidential vote in 2016, and whether challengers will face an incumbent or vie for an open seat. And we took cues from the parties themselves, each of which have identified their own target lists of vulnerable candidates and flippable seats.

Competitive Seats: United States Senate

Click on each candidate for an analysis of his or her race.

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Incumbent Competitive Analysis for the Senate 2018 Midterms
State Incumbent Party Margin of Victory 2016 Presidential
Latest Prediction  

*Based on a weighted average of election predictions by the three leading election-analysis sites, the Cook Political Report, Inside Elections, and Sabato’s Crystal Ball.

Tracking the Most Competitive 2018 Senate Races