Democratic candidate Lauren Arthur won a special election for a formerly GOP-held Missouri state Senate seat Tuesday night by a 20-point margin.
That’s the 42nd state legislative seat Democrats have flipped since Donald Trump’s inauguration, and though that only slightly reverses Democrats’ massive down-ballot losses during the Obama administration, it’s a pretty solid down payment considering that few seats have been up so far.
Both Trump and Mitt Romney won this seat by a 4-point margin, so the Democratic victory amounts to a 24-point improvement on their presidential candidates’ performances in 2016 and 2012.
Democrats are cleaning up in special elections
According to an extremely useful comprehensive spreadsheet compiled by Daily Kos, across 70 special elections in 2017, Democrats ran 10 points ahead of Clinton and 7 points ahead of Obama’s 2012 results. Those numbers have accelerated into 2018. Across about 50 races, Democrats are running 13 points ahead of Clinton.
Historically speaking, special election results usually are somewhat predictive of midterm general election outcomes, and Democrats have generally done somewhat better in these actual electoral contests than their generic ballot polling lead would suggest.