Presumably if Harold Ford is going to beat Kirsten Gillibrand his two bases of support in the primary are going to be blacks and conservatives.
Looking back at the exit poll from the 2008 primary in New York 16% of voters were African American and 9% identified themselves as conservatives. Making the very unrealistic assumptions that there's no overlap in those groups and that 100% of them would vote for Ford that puts him at 25%.
Hard to see where he gets the other 25% with the rhetoric he's putting out there. His behavior is certainly a head scratcher.