Everyone has interesting and valid things to say about this, especially HotBulge & njqt466.

Although I don't think racism is as much of a problem as it was back in the 50s and 60s, it's still a factor in everyday life. Obama is destined to receive opposition from those with this archaic ideals and beliefs about people who are different from themselves. And as marleyisalegend pointed out, it makes things even more difficult when press outlets protray certain races with a negative bias, whether it be direct or indirect. It'll be a major test for Obama to see if he can win over some of the states where this bias towards black people runs the strongest if he does secures the nomination.

Obama has won these states in the primary: Alaska , Alabama, Colorado, Connecticut, Delaware, Georgia, Hawaii, Idaho, Illinois, Iowa, Kansas, Louisiana, Maine, Maryland, Minnesota, Mississippi, Missouri, Nebraska, North Dakota, South Carolina, Texas (caucus), Utah, Vermont, Virginia, Washington, Washington D.C., Wisconsin, and Wyoming.

16 out of 28, or 57% of these victories are in states that voted for the Republican Candidate at least 4 out of the last 5 presidential elections. The big states that usually go Democratic went to Clinton. If racism remains a major issue for Obama, then this can spell trouble for him in November.