The polls were wrong again.
They predicted a narrow Clinton win, but we got a narrow (but comfortable) Sanders win.
But take a look at this tweet from Nate Silver:
Notice the time. This is not hindsight.
The polls were wrong, but the demographics-based model got it right.
The Michigan polls were deadly wrong, but, if I remember correctly, the demographics pointed to a Sanders advantage.
It’s been true throughout the whole primary season. To know who will win a state, just look at the demographics.
Clinton wins minorities, older than 45 and registered democrats. Sanders wins whites, younger than 45 and independents. This has been the pattern. It doesn’t seem to matter the state’s place in the calendar. Or “momentum”.
The patterns are set. No reason to believe they will change.