Race and Tennessee
A pretty good case can be made that the two most talented younger Democrats are African-Americans: Barack Obama and Ford. But where Obama represents a state that has been probably the single most favorable state to black candidates running statewide, Ford is from Tennessee. Democrats haven't won a Senate race in Tennessee since 1990--in fact, they haven't even come close to winning a Senate race in Tennessee since that time. (Twenty years ago, Tennessee had the most liberal Senate delegation in the South, Albert Gore and Jim Sasser.) Ford is far and way the strongest candidate the Dems could offer in the state--telegenic, very bright, smart politically. But in a state where the Republicans have a built-in advantage, it's hard to see an African-American winning.
The Cohen victory is even more unusual. Brooklyn College's congressional district is experiencing a similar House primary, as a white candidate, David Yassky, is attempting to win a majority-minority seat. As with Cohen's race, the black vote is divided. Cohen is likely to win in November, though Ford, Jr.'s brother is running as an independent in a district that has been represented by a Ford continuously since 1974. But his chances of being more than a single-termer seem remote: African-American candidates took more than 60% of the vote in the primary, and had a single black candidate run, Cohen almost certainly would have lost.
I believe that Peter Rodino's Newark district was the last majority-minority district to pass from white to African-American representation. It would indeed be an irony were 2006 to feature two such districts moving in the other direction.