In this photo taken May 2, 2012, U.S. Congress candidate Taj Clayton, left, listens to a campaign worker at his headquarters for the 30th Congressional District race, in Desoto, Texas. For two decades, Eddie Bernice Johnson has been an outspoken voice for Democrats in a bright blazer and multicolored scarf. But for the first time, the first black woman to represent North Texas in Congress is facing serious opposition in this month's primary. And the effort to unseat her is just one of several challenges being mounted against some of the longest-serving blacks in Congress. (AP Photo/LM Otero)