Senate Update - 8 October

Last night and much of today, the political world was abuzz with news of a new poll out of South Dakota.  The poll, by SurveyUSA, found the Republican, Mike Rounds, stuck in a tighter-than-expected three-way race.  He was leading the Independent, Larry Pressler, by only three points, while the Democrat, Rick Weiland, was four more points behind.  

The reason this is such a huge development is that before this poll, it was thought that South Dakota was a safe pickup opportunity for the GOP.  Without it, they would need to win at least six seats elsewhere, no small feat.  

However, we must caution that this is just one poll.  Despite Nate Silver's Fivethirtyeight ranking Survey USA as one of the 'best' pollsters in the country, we cannot put too much weight on the result until more polls are released showing similar results.  If and when that happens, the model will begin to reflect those changes (we found that if only the SurveyUSA poll was applied to the model, Democrats would have a 19% chance in the state and a 50% chance overall).  Until now, we have the GOP with a 54.6% chance of winning the Senate.

Besides the South Dakota poll, there were a number of other polls released today, mostly from Fox News.  The polls mostly look bad for Democrats.  It had the GOP candidates in Kansas, Colorado, Arkansas, Kentucky, and Alaska up by 5, 6, 7, 4, and 4, respectively. 

However, as Fivethirtyeight noted, Fox News surveys have been strongly favoring the GOP candidates.  In fact, the lean Nate Silver's site has calculated for Fox News' polls is approximately 3.5% towards the Republicans.    

At Battleground270, we have yet to begun adding in corrections to polls based on the pollster's lean, and it would be unfair to begin adding that in now to just these polls.  However, to account for the drastic lean these polls have towards the GOP, we are just rounding down the averages to the nearest 0.5%.

For example, if the average polling lead (based on RealClearPolitics list of polls) for the GOP candidate is 4.3%, and one of the polls is from Fox News, Battleground270's model will automatically round that down to a 4.0% lead for the GOP candidate.  

Finally, SurveyUSA found Georgia Democratic candidate Michelle Nunn up by one point, the first poll to find her leading Perdue in the past month.  Multiple polls have shown the race within the margin of error, and this could be the first one to show the effects from Perdue's outsourcing comments fallout.