A reader writes:

In states where the black population is less than 5%, Obama has a record of 7 wins, 2 losses and 1 undecided (NM).   In states where the black population is 20% or higher, he is undefeated at 4-0. However, in states that are between 5-20% black, his record is a fairly dismal 4-10 (with one of those victories being Illinois).

The theory here is that Obama does well where the black population is so low that identity politics isn’t an issue.  And, he does well where the black share of Democratic primary voters is so high that he needs few white voters to carry the day.  He has the hardest time in states that are black enough to have some racialized politics, but without enough black voters to completely tip the scales.

This corresponds to the long held observation that black candidates in general do best in either fairly non-black environments or in heavy black environments but struggle with the in between, where white majority fears that they will be the tool of an aggrieved constituency.  (Some, of course, have broken that mold like Doug Wilder, and Carol Mosely-Braun and Obama himself).

For Obama’s upcoming contests, this bodes well for Maryland, D.C., Virginia, Nebraska and Vermont and maybe Rhode Island, but not so well for Ohio and Texas.