2. Obama's (2-party) 59% share of new voters is equal to his 2008 exit poll share. He had 73% of new voters (2-party) in 2008.
There are two sets of scenarios:
1) 2012 Vote shares
Base Case: Obama has 92% of Obama and 5% of McCain voters.
(3% net defection of returning Obama voters for Romney).
2) Returning 2008 Voter turnout
Base case: Equal 92% turnout of living Obama and McCain voters.
Base Case: Obama wins by 16 million votes with a 56.4% (two-party) share.
I. 2012 Vote shares: Worst case scenario
Obama has 88% of returning Obama and 1% of returning McCain (net 11% defection advantage to Romney).
Result: Obama has 52.8% (2-party) and wins by 7 million votes.
II. 2008 Voter turnout: Worst case scenario
77% of living Obama voters and 100% of McCain voters turn out.
Result: Obama has 51.8% (two-party) and wins by 4.5 million votes.
This scenario matches the recorded vote.
Late Vote Share vs. Election Day Share