The Role of African-American vote in the Democratic Party Primaries

The Democratic party presidential primaries have produced an enigmatic phenomenon.

In predominantly white electorate states (where the African-American electorate is less than 5 percent) such as Iowa and Wisconsin, Senator Obama has drawn large percentage of the White electorate votes -- large enough (more than 40 percentage of the votes) to win those primary elections handily.

Similarly, in primaries with very large African-American electorate (20 percent and more) and even larger African-American vote participation (25 percent and more) such as South Carolina, Georgia and Louisiana, Senator Obama again has won handily -- but this time with significantly smaller share (less than 30 percent) of the participating white votes and overwhelming support from very large percentage from the African-American votes. The participation of the African-American electorate in these states was over 40 percent.

And then, in states (e.g. Massachusetts, New Jersey, and Ohio) with moderate percentage of African-American electorate and votes Senator Obama has not been able to draw enough white electorate votes to overcome only a modest percentage (15 - 30 percent) from the African-American vote.

The empirics suggest that the relationship between the probability of Senator Obama's victory in a democratic primary election and the percentage of the African-American population and vote is a U-shaped function.