The Senate Races3 September 2016

We start with the basic numbers. The Republicans have 54 Senators as of today. A total of 34 seats are up for grabs, 24 of them currently held by Republicans and 10 held by Democrats.

Republican seat overview: 12 of the 24 races have polling data. Of those 12, the Democratic challengers are favored to win 5 and the Republicans to hold the position in the remaining 7.

Democratic seat overview: 4 of the 10 races have polling data, Of those, 3 look good for the Democrats and Nevada looks close, currently favoring the Republican candidate.

The overall odds looking at the ten closest races. The information in the first three paragraphs is exactly the same as last week. The important changes that happened are in the probabilities of victory in two races, Wisconsin and Ohio. Rob Portman's lead in Ohio looks stronger now, so the race is no longer one of the 10 closest and Ohio will very likely stay in Republican hands. Instead, the race in Wisconsin is the tenth most closely contested, with Russ Feingold still favored to unseat the Republican incumbent Ron Johnson. The chances for how many seats the Republicans will hold now look like this.

Here are the changes from last week:

Probability of Republicans holding the Senate outright: 26.1%, up from 12.6%
Probability of a 50-50 split: 37.0%, up from 34.3%
Probability of the Democrats taking the Senate back: 36.8%, down from 53.1%

Races that look close.
1. Nevada is closest and it favors the Republican Joe Heck over Democrat Catherine Cortez Masto, vying for the seat being vacated by Harry Reid. This would be a gain for the GOP.
2. New Hampshire is next closest and Kelly Ayotte is trailing her Democratic challenger Maggie Hassan. This would be a loss for the GOP.
3. In North Carolina, incumbent Richard Burr leads challenger Deborah Ross. This would be a hold of a seat for the GOP, so no net gain.
4. In Pennsylvania, GOP incumbent Pat Toomey is trailing challenger Katie McGinty. This would be a loss for the GOP.
5. In Wisconsin, Russ Feingold is a solid favorite to beat Ron Johnson, but the current Confidence of Victory number is slightly under the arbitrary 90% mark I count as the threshold between contested and not contested.

Back tomorrow with the numbers in the presidential race.