Why does the MSM distinguish between 'liberal' and 'black?'

Mimi Hall ponders in USA Today whether President Obama is losing control of liberal Democrats.  According to the White House, the answer is ‘no':

White House spokesman Robert Gibbs routinely brushes off questions about whether Obama and the Democrats are losing key constituencies, but he says the notion that the president is taking liberals for granted is "silly."

Mr. Gibbs would seem to be correct given recent poll numbers:

Polls show those who represent a significant chunk of Obama's base still back him. Although the samples are small and the margins of error high, a USA TODAY/Gallup Poll taken in January found that nearly nine in 10 blacks approve of the job Obama's doing, as do more than seven in 10 liberals.

Question:  Since a relatively narrow segment of the population (blacks), and a broader selection of the population (liberals) agree in their approval of Mr. Obama, why bifurcate their poll responses?  As the article says, "Polls show liberals and blacks still approve of the job Obama's doing,"

When is the last time you saw the MSM draw a distinction drawn between ‘conservative' and ‘white'?  Bush-43 ended his tenure with approval numbers significantly lower than the temperature surrounding Al Gore (wherever he may be), but we never read that Bush was in danger of losing the ‘white' vote.

Liberals accuse conservatives of being: racists, dumb, Nazis, rednecks, prejudiced, in-bred, uneducated, and closed-minded, etc.   But, it is liberals who refuse to stop separating the races; it is the progressive left that uses race as a tool of division. 

Divide and conquer.

Mimi Hall ponders in USA Today whether President Obama is losing control of liberal Democrats.  According to the White House, the answer is ‘no':

White House spokesman Robert Gibbs routinely brushes off questions about whether Obama and the Democrats are losing key constituencies, but he says the notion that the president is taking liberals for granted is "silly."

Mr. Gibbs would seem to be correct given recent poll numbers:

Polls show those who represent a significant chunk of Obama's base still back him. Although the samples are small and the margins of error high, a USA TODAY/Gallup Poll taken in January found that nearly nine in 10 blacks approve of the job Obama's doing, as do more than seven in 10 liberals.

Question:  Since a relatively narrow segment of the population (blacks), and a broader selection of the population (liberals) agree in their approval of Mr. Obama, why bifurcate their poll responses?  As the article says, "Polls show liberals and blacks still approve of the job Obama's doing,"

When is the last time you saw the MSM draw a distinction drawn between ‘conservative' and ‘white'?  Bush-43 ended his tenure with approval numbers significantly lower than the temperature surrounding Al Gore (wherever he may be), but we never read that Bush was in danger of losing the ‘white' vote.

Liberals accuse conservatives of being: racists, dumb, Nazis, rednecks, prejudiced, in-bred, uneducated, and closed-minded, etc.   But, it is liberals who refuse to stop separating the races; it is the progressive left that uses race as a tool of division. 

Divide and conquer.