The poll, by Mason-Dixon Polling & Research, shows Sen. Barack Obama leading Sen. John McCain 47 percent to 45 percent, well within the poll's 4-point margin of error. With the race essentially tied going into the last lap, Florida's 27 electoral votes remain the biggest battleground prize for either candidate.

If Obama wins here, he is virtually assured the presidency. If McCain loses, his candidacy is all but dead. Mason Dixon Polling & Research interviewed 625 likely voters Wednesday and Thursday.