2018 Midterm Election Odds: GOP a Large Favorite to Retain Senate Majority

2018 Midterm Election Odds: GOP a Large Favorite to Retain Senate Majority article feature image

Credit: Kyle Grantham/The News Journal via USA TODAY NETWORK

  • Many seats are up for grabs in the midterms for the Senate, and stakes are high for both parties considering the current political climate.
  • Oddsmakers lists Republicans at 75% implied probability (-300) to retain control of the Senate in November.
  • Smarkets is the highest on the possibility of no majority and lowest on the possibility of a Democratic majority.

Considering the current political climate, increased partisanship within U.S. politics and the ongoing Russia investigation by special counsel Robert Mueller, the 2018 midterms in November come with stakes as high as we’ve seen in a long time.

The GOP currently controls all three branches of government — and the Supreme Court will become even more conservative if new appointee Brett Kavanaugh is confirmed — so any shift to Democratic control will certainly change the dynamics of U.S. politics.

On that note, let’s look to the betting market to see which party is likely to have control of the Senate come November. We’ll also post odds on the House later this week and make sure to update these pieces as the betting market shifts.

If the past two years have taught us anything, it almost assuredly will.

First, here are the odds (listed as implied probability), PredictIt and Smarkets for which party will have the Senate majority after the midterms.

The markets are all fairly in line: Republicans are a large favorite to retain control of the Senate in November. While PredictIt did not list odds for no majority (if it ends up a 50/50 split), and Smarkets are somewhat far apart in their implied probabilities.

While has the same odds (+450) for both a Democratic majority or no majority, the Smarkets probabilities suggest a 50/50 split is much more likely (28.6%) than Democrats winning over the Senate (9.1%).

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PredictIt allows speculators to buy shares on how many Senate seats the GOP will hold after the 2018 midterms — from 60 or more on down to 49 or fewer.

While “49 or fewer” is the single-most likely outcome of all of these, it’s also the only one that gives Democrats the majority. Interestingly, that’s actually slightly lower than the overall odds for Democrats in the first prop listed above. The next most likely outcome is 50 seats (no majority), and then there’s a predictable curve toward a GOP landslide. As expected, the most likely GOP majority scenario appears to be a 51-49 split.

Stay tuned for more politics betting content, and we’ll make sure to update you as the markets shift over the coming months.

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