December Signs of a November Wave

 In Defying the Odds, we discuss congressional elections as well as the presidential race.

Mark Murray at NBC:

Fresh off their victory in Alabama’s special Senate election, Democrats now enjoy their largest advantage in congressional preference in nine years, according to the latest NBC News/Wall Street Journal poll, signaling a dangerous political environment for Republicans entering next year’s midterm elections.

Fifty percent of registered voters say they prefer a Democratic-controlled Congress, versus 39 percent who want Republicans in charge.

Harry Enten at FiveThirtyEight:

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, naturally, 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 the partisan lean of that state or district2 — 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 the partisan lean of that state or district. Instead, Democrats have outperformed the partisan lean in 74 percent of these races.