Some mistakes in a campaign have a very limited half-life. That was true of Obama adviser Samantha Power's statement that Hillary Clinton is a "monster" -- an obvious lapse into hyperbolic trash talk that simply reflects the Obama team's anger over the New York senator's tactics. Power resigned.

Others loom larger -- with longer-lasting effects. We may have just seen one of those in the comments of Clinton supporter Geraldine Ferraro, the 1984 Democratic vice presidential nominee. "If Obama was a white man, he would not be in this position," she told a California newspaper.