Since the 2012 elections, there’s been an extended debate over the strength of the current Democratic majority and the future viability of the Republican Party. I’ve long argued that these postmortems are overwrought, and nothing about the results altered that. After all, the demographic changes in that election were more attributable to a surprisingly large number of white voters staying home (fewer whites voted last year than in 2004, despite steady growth in absolute numbers) than to any rapid growth in minority votes. The GOP performed about as well in November as we would have expected given the state of the...