A judge on Friday denied an effort by former New Orleans Mayor Ray Nagin to postpone his corruption trial, which he said had been compromised by inflammatory comments posted online by prosecutors. Nagin’s argument for a delay stemmed from online postings that recently prompted a federal judge to order a new trial in a murder case involving five New Orleans policemen convicted in connection with the shooting deaths of two unarmed people at Danziger Bridge after Hurricane Katrina. … Nagin, who was mayor during Hurricane Katrina in 2005, is accused of receiving kickbacks in exchange for city contracts, and wire...