A note on generic ballot measures. The generic ballot measures you’re seeing (generally, D+3 or +4 right now) are a biased estimate of vote share in next year’s election. They’re biased because parties don’t run generic candidates: they run actual ones, and that means Dems are likely to do better.
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Unless Dems run terrible candidates, no? Seems like this happens w some regularity
Yes, it’s all based on candidate recruitment. If the most qualified candidates stay in the State House (or wherever), their party underperforms.
This is based on a study I published 7 or 8 years ago, but the data holds up. The best predictor of deviation between the House generic ballot (right before the election) and actual results is the state of the economy and the President’s approval 12 months before the midterm.
The President’s Party benefitting or being punished for his popularity and the state of the economy isn’t surprising, but the lag is: why a one-year lag? Shouldn’t it be approval and the economy on the cusp of the election?
The key is that about one year out- so about 2-3 months from now- is when candidates are deciding to run. If things look good, highly qualified candidates throw their hats in the ring. If not, they stay in the jobs they have now.
So, in 2-3 months, qualified Republican candidates are going to look at Trump’s approval and economic indicators, and likely say, “I’ll wait for 28 or 30.” Dems who have been thinking about it are going to jump in.
As such, the median Democratic candidate is likely to be *better* than a generic Democrat, and/or the median Republican candidate is likely to be *worse,* thereby overperforming or underperforming the expected generic ballot vote.
There’s also a lag effect- if a party outperformed last cycle, they do worse this cycle- but that’s also a candidate selection effect. If a party had a good environment last time, they need time to rebuild the bench.
Either way, it’s all candidate selection. If Dems or Republicans do well in the midterm, it’s not just national trends: it’s the rational decisions of the most qualified candidates to run, or not.