Not racist..Just curious..?

Why alot of African Americans I come across hate republicans? Abe Lincoln was a republican president-and he helped abolish slavery..This question is stemming from a comment I heard someone make about how they were voting for Obama because he's black..Also, why do SOME (not all) African Americans blame White people's ancestors for slavery when in reality-it was THEIR PEOPLE who sold them to the white people in the first place...Again-I'm not trying to start a racist fight-I just want some legitamte point's of view from MATURE, OPEN MINDED people..Thanks.