"Early on, African-Americans threw their support to Hillary Clinton, primarily based on the Clinton legacy. However, as African-American voters have gotten to know Barack Obama, support for him has increased significantly. The real tipping point in the Democratic primary election may be undecided African-American female voters -- there are many more African-American female undecideds than males, and Clinton and Obama are dead even among African-American women. It may literally come down to whoever gets the African-American female vote.
I believe Hillary is running on two things: 1) name-brand recognition; and 2) Bill nostalgia.
The problem that Hillary is facing though, is that a lot of people have already made their minds up about her, and I don't think her numbers can move too far from where they are right now. Also, there's the reality that Hill is not Bill--and using her husband as an attraction to draw people in will only go so far.
There are a lot of people out there (especially those across the digital divide who don't get their information from the internet), who simply don't know WHO Barack Obama is. They have all sorts of misconceptions, like "Is he a Muslim?" or aren't aware of his background as Constitutional scholar, civil rights attorney, and community organizer.
But Obama has nowhere to go but up. Once people get to know him, his numbers will only rise.