Long-simmering racial tensions exploded into the foreground Saturday morning, when Assemblyman Keith Wright accused supporters of State Sen. Adriano Espaillat, Wright's leading opponent in the race to succeed U.S. Rep. Charlie Rangel, of plotting to “suppress” and block African-Americans from voting in Tuesday’s Democratic congressional primary.The accusation — first made in a brief interview with POLITICO New York Friday evening — was aired again during a nationally broadcast gathering in Harlem Saturday, hosted by the Rev.