Meanwhile, institutions that were seen as outside or sideways to political debate have been enlisted in the culture war. The tabloid industry gave us the apotheosis of Caitlyn Jenner, and ESPN gave her its Arthur Ashe Award. The N.B.A., N.C.A.A. and the A.C.C. — nobody’s idea of progressive forces, usually — are acting as enforcers on behalf of gay and transgender rights. Jock culture remains relatively reactionary, but even the N.F.L. is having its Black Lives Matters moment, thanks to Colin Kaepernick.

For the left, these are clear signs of cultural gains, cultural victory. But the scale and swiftness of those victories have created two distinctive political problems for the Democratic Party.