Biden’s advantage shrinks among key voters

Next week the Democratic nominating process moves to South Carolina and to a very different electorate. For months, the state’s African-American population has been seen as a kind of firewall for former Vice President Joe Biden – a group of voters who would support him even if he had a tough first few contests.

But new numbers from the latest NBC News/Wall Street Journal poll suggest that theory may be a little simplistic and the biggest gainer in Biden’s early struggles may be Vermont Sen. Bernie Sanders. CONT.

Dante Chinni, NBC News