NC-09: Democrats Scored a Big, Unexpected Win in the May 8 Primaries
Primarily, at the hands of Mark Harris, Republicans now do not have the advantages that fielding an incumbent representative presents in a district. This is an easily quantifiable phenomenon. Whether it be because incumbents have bigger war chests to spend on reelection efforts, because they have valuable name recognition, or something else, they generally perform better than their unelected counterparts.
In an analysis I wrote last summer, I found that incumbency was worth roughly 7 percentage points in the 2016 U.S. House elections. That is, incumbent Democrats saw a 7 point increase in their expected margin of victory over Democrats running in open seats. The advantage was roughly equal for Republicans.
So what does that mean for the November midterms?
In NC-09, this means that where the Republicans had a ~7 point advantage1 over a generic Republican by having Rep. Pittenger carry their banner, they now have a generic Republican — in pastor Mark Harris — that does not give the GOP the resources or name recognition that they would otherwise have. Their chances of holding the seat fall accordingly.
In quantitative terms, the news might sound even better for Democratic analysts. My 2018 U.S. House forecasting model, ran with Pittenger as the candidate, estimated that Democrats would lose the seats by 10 points and had just a 25% shot at winning the district. However, changing the candidate to Harris — thus removing the advantages that incumbency presents — and rerunning the model, our best prediction is now a 2 point Republican victory and a much bigger 45% chance of Democrats flipping the seat. In familiar ratings-based terms, my prediction for NC-09 just went from Lean Republican to a pure Tossup. Pittenger’s loss in North Carolina’s 9th Congressional District is a huge deal, in short.
http://www.thecrosstab.com/2018/05/08/may-8-recap/
