With a large and stable lead in the polls, an even more favorable lead in the electoral analysis, and a huge amount of money in the bank the Obama campaign juggernaut looks very hard to beat:
"The Bradley Effect", where polled people tend to vote differently than they tell the pollsters due to race, seems unlikely to play a role although some think this may work against Obama in the final tallies.
Clearly the most important factor at this late time is the mother's milk of American politics....money. Obama's campaign raised a jaw-dropping 150 million in September and will be able to outspend McCain by something like 3 to 1. This is a huge advantage and makes it much harder for McCain to "raise his voice" and profile in the public eye at this critical time.