Democrat Doug Jones’s stunning victory in Alabama on Tuesday should send a shiver down the spine of GOP elected officials everywhere. Yes, Jones likely would have lost the special election for a U.S. Senate seat had his Republican opponent, Roy Moore, not been an extremely flawed candidate. But Moore’s defeat is part of a larger pattern we’ve seen in special elections so far this year, one in which Democrats have greatly outperformed expectations. If history holds (and of course, it may not), the special election results portend a Democratic wave in 2018.
There have been more than 70 special elections for state and federal legislative seats in 2017 so far.1 We’re interested in each of those contests, of course, but we’re also interested in what the races tell us about the national political environment. To measure that, we compared each special election result to that state or district’s partisan lean2 — how we’d expect the state or district to vote in a neutral environment (i.e. an environment in which a Democratic and Republican presidential candidate would tie 50-50 nationally).
So, in a neutral environment, we’d expect each special election result to match that state or district’s partisan lean. Instead, Democrats have outperformed the partisan lean in 74 percent of these races.
The Democratic margin has been 12 percentage points better, on average, than the partisan lean in each race. Sometimes this has resulted in a seat flipping from Republican to Democratic (e.g. in the Alabama Senate face-off on Tuesday or Oklahoma’s 37th state Senate District contest last month). Sometimes it has meant the Democrat barely loses a seat you wouldn’t expect a Democrat to be competitive in (e.g. in South Carolina’s 5th Congressional District in June). Sometimes it’s merely been the case that the Democrat wins a district by an even wider margin than you’d expect (e.g. in Pennsylvania’s 133 House District last week).
The point is that Democrats are doing better in all types of districts with all types of candidates. You don’t see this type of consistent outperformance unless there’s an overriding pro-Democratic national factor.
And to be clear, although there have been more special elections on the state level, the pro-Democratic environment is quite clear if you look only at federal special elections. There have been seven special U.S. House and U.S. Senate elections so far this year. The Democrats have outperformed the partisan lean in all of them.
Gosh, what national factor boosting all types of Democrats in all types of races in all types of locations could be responsible for such over-performance?
It's a mystery, you guys.