Insider Advantage's latest survey projects that black voters will comprise 35% of all who turnout on Tuesday, which seems a little low, but may well be in the ballpark of the reasonable. Obama leads Clinton by four points, with Clinton taking nearly 60% of the white vote and nearly doubling her usual percentage of the black vote (17%). The (relatively) small lead for Obama here is directly related to Clinton's performance among black voters. Mason Dixon's most recent poll, for example, have Obama an eight point lead overall having taken 87% of the black vote in an assumed electorate where blacks make up around 40% of the total. Mason Dixon, like virtually every recent survey, real or robotic, gives Clinton about 60% of the white vote. Most NC polls peg black turnout as being between 32 and 34% of the electorate.
This real cool spreadsheet helps make the point. Let's be generous and give Clinton 17% of the black vote and 63% of the white vote. Let's then assume that black voters make up 35% of the electorate. Obama wins by 8 points. What's a scenario where Clinton wins? Let's award her 65% of the white vote and 18 percent of the black vote, and let's assume that black turnout dips to about 29% of the electorate. Clinton wins here by a half a point.