Well listen to what the supposed "first black President" had to say about the enlightened voters pulling the donkey-lever:
From this source:
Voting for president along racial and gender lines "is understandable because people are proud when someone who they identify with emerges for the first time," the former president told a audience while campaigning for his wife.
There you go, folks. A Democratic former President has just given you permission to vote for the candidate that looks the most like you.