The great realignment

Shifts in the demographics of the two parties' supporters — taking place before our eyes — are arguably the biggest political story of our time.

The big picture: Republicans are becoming more working class and a little more multiracial. Democrats are becoming more elite and a little more white.

Why it matters: Democrats' hopes for retaining power rest on nonwhite voters remaining a reliable part of the party's coalition. Democrats' theory of the case collapses if Republicans make even incremental gains with those voters.

Even small inroads with Hispanic voters could tip a...