President Obama and Mitt Romney are locked in a virtual tie in Florida, according to a Miami Herald/El Nuevo Herald/Tampa Bay Times poll that indicates the Democrats’ convention buzz and the Republican’s recent troubles haven’t altered the race in this biggest of battleground states. Obama is drawing 48 percent support to Romney’s 47 percent among likely voters — a lead well within the poll’s 3.5 percent error margin. Only 4 percent are undecided. “Despite what some people have tried to claim, this race is still close in Florida,” said Brad Coker, who conducted the Mason-Dixon Polling & Research survey. “It’s...