I really think it is a combination of many different factors. To say it is the fault of one source, a certain party, or "Black leadership," is misguided. What exactly do you mean by black leadership? There are very many political leaders in the African American community, but they all have different backgrounds and different political ideologies. To group Ben Carson, Barack Obama, Martin Luther King Jr., and Marcus Garvey, among others, in the same category and to say that they all seek the same goals is laughable. One could say Democrats and Republicans have jointly allowed it to happen. This doesn't restrict itself to the plight of African-Americans: people of every race who suffer from poverty can look to the failed leadership of both parties, who have held a duopoly on American politics, with very few exceptions, for over a century. One of the largest and most noticeable results of this duopoly between a right-wing and centrist party is the absence of a universal healthcare system when one exists in virtually every country in the industrialized world. This leads to higher poverty rates which negatively affect the African-American population.
However, I have something to add about the phrasing of the question. If we continue the premise is that we are thinking of the problems of African-Americans as separate from the rest of the U.S., we can never truly never solve the issue of racial inequality. Racially focused social programs, while well-intentioned, create a mindset in society that one race is more "deserving" of benefits than another, according to the government, and therefore creates racial tensions. What is needed is social programs such as class-based affirmative action that will aid all people in poverty regardless of race. If the government continues to operate by using racially biased policies, one can guarantee that the populous will have racist sympathies in one direction or the other.