Theories of Representation

There's a fascinating little story unfolding in a congressional election in Memphis where a white man, Rep. Steve Cohen, replaced Rep. Harold Ford, Jr., when Ford ran for the U.S. Senate. Now Cohen faces Democratic primary opposition from an African-American woman who is, according to some progressive voices, less likely to represent the economic interests of the largely black and quite poor district. Cohen's voting record rated higher than Ford's on the report cards of the Congressional Black Caucus, and his positions on report card issues are consistently more aligned with the CBC than are his opponent's.
There's a strong gay-bashing undercurrent to the race, as well.
All of it makes me wonder about theories of democratic representation. Who can represent whom? Can a white man adequately represent the interests of black folk? Can a straight man adequately represent the interests of gay men? What of the interests of women? Children? Old folks? Muslims? Atheists? Rural folks? What of the interests that cross the lines of interest group politics?
Interesting.