ST. LOUIS (AP) — The next mayor of St. Louis will face the same overwhelming challenge that has haunted the current mayor and many of her predecessors: Violent crime is rampant, and efforts to address it have failed. Four mayoral candidates will square off in a primary election Tuesday, with the top two vote-getters meeting in a general election in April. Whoever wins faces a daunting task. The homicide rate in St. Louis has been among the worst in the nation dating to at least the 1990s. Beyond the heartbreak for the victims and their families, the crime drives away residents and business.