Okay, this might show why some polls have Obama with a double digit, but it is highly unlikely:
Assuming 130,000,000 DEM 40 REP 32 IND 28
Obama Would Need 71,500,000 votes
McCain Would Get Only: 58,500,000 votes
Carrying 90% of DEMS would give Barry 46,800,000
Carrying 11% of REP would give Barry 4,576,000 votes
Of the 28% IND Votes, Obama, would need to get 55% of them or 20,200,000 votes to get 55% of the total vote.
So the only way for Barry to win by double digits is to carry 90% of Democrats. It this going to happen? The estimated averages of the PUMA’s are around 15% according to Zogby. But that only reduces the total vote number by about 2 million, so McCain has to hold a larger portion of the GOP voters (around 92-93%) and get the independents even (50-50 or 51-49) and then McCain can win, even using this model of the Democratic oversampling.