Breaking it down.
1:

In Maryland, where blacks make up about 30 percent of the electorate,

2:

the Democratic candidate for governor, Martin O’Malley, who is white,

3:

is trailing the Republican incumbent, Robert L. Ehrlich Jr., by several points.

Notice that it begins with the black electorate, follows with pointing out O’Malley is white, and finishes with GOP incumbent Ehrlich’s lead without pointing out he is also white which leads a reader to link him back to the black electorate point at the beginning.

Unless, of course, they assume their readers all know that Erhlich is white and would immediately associate someone with the surname O’Malley as black.

Perhaps I’m reading too much into it, but the paragraph in the article devoted to Claire McCaskill here in Missouri contains a whopper, also.

In Missouri, Claire McCaskill, the Democrat trying to unseat Senator Jim Talent, has been running advertisements about sickle cell anemia, a genetic illness that mostly afflicts black people, and the importance of stem cell research in helping to find a cure.

McCaskill has been running ads about stem cell research in general and her support of Amendment 2: Stem Cell Research and Cures Initiative, while attacking Talent’s opposition to the amendment.

Jim Talent is the one that has been running sickle cell anemia ads touting the Sickle Cell Disease Treatment law he co-sponsored with Chuck Shumer while attempting to skirt his party affiliation. Check out the “African Americans for Talent” page of his campaign web site if you can stomach the pandering.