I think there is a causal connection between the two. A big chunk of those 43% whites that view Dems unfavorably do so, for the most part, because 72% of blacks views it favorably. Stated differently, Dems are often seen as a "black" party and that turns many whites off without even examining Democrat position on issues that affect them.
Lest it be interpreted as a simplistic "racism" story (which imho is a rather amorphous and ambiguous concept) - it is more complex than that, specifically, a reference group identity politics. A big part of the "middle class" identity is knowing that there are groups below them in the social ladder. Without that, the whole concept of the middle class does not make any sense. Blacks usually serve as such a negative reference against which these people define their own status (which involves prejudice, to be sure). Therefore, rejecting the "party of blacks" - Democrats - and supporting Repugs is one of many ways that give these folks a delusion of a higher social status. You can hear this logic - very thinly veiled - from white suburbanites all the time.
Wojtek