As the nation's first African-American president, Barack Obama benefited from and expanded his party's enormous advantage among minority voters.

But as he prepares to start his second term, Obama hasn't managed to usher in behind him many Democrats who are minorities to top elected office. Conversely, Republicans — despite their highly limited support among non-Anglo voters — have managed to elevate more top politicians from minority backgrounds.

"It's just an objective, empirical fact that more members of minority groups have done well winning in the Republican Party," says Artur Davis, a former Democratic congressman from Alabama who has switched allegiance to the GOP.

"The Republican Party has proven welcoming to minorities, and its voters will elect minorities as long as those minorities share their worldview, as long as those minorities are conservatives," Davis says.

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Still, reaching the top rungs can be difficult for African-American politicians in particular — because the vast majority of those holding elected office are in the South.

Neither Davis nor Ford was able to win election, and other blacks nominated to statewide posts in the South have done even more poorly.

In addition to the region's conservative nature, in the Deep South, "in terms of statewide elections, there's high racial polarization," says David Bositis, an expert on black politics at the Joint Center for Political and Economic Studies.

Read more at NPR.