Why can't Barack Obama close the deal?
Just before he lost in Pennsylvania Hillary Clinton taunted Obama with that question.
One reason could be race.
In an exit poll one in five Pennsylvania Democrats said the race of the candidate was "important" to their decision.
Many had seen clips of Obama's pastor, Reverend Jeremiah Wright, cursing America, implying that the 9/11 attacks were justified.
Obama won big in Pennsylvania's African American wards, but lost nearly everywhere else.
Wright defends Obama to Bill Moyers in an interview to air Friday night on PBS.
Obama's next big test will come in Indiana on May 6th.
"Barack needs to be himself. He just needs to show, the same way he got elected in Illinois, that he can go in Chicago and communicate with workers about their worries," said Obama supporter and former Indiana Congressman Tim Roemer.
Uncommitted super delegate Brad Miller, is watching and worrying.
"Whoever our nominee is, and I expect that it will be Senator Obama, I think needs to make a greater effort in the general election to appeal to the constituencies in the Democratic party that they did not do as well with in the primaries," Miller said.
It's not just Obama's burden.
Hillary Clinton has to prove on May 6th in North Carolina that she can win black votes.