I think the race is likely over. Obama threw the election for some reason, and now Romney is going to win. He'll win narrowly, but a win is a win.
Any such chart (I guess it is your sig chart) needs to be on a per capita basis since the US has more population growth the Britain.
In the meantime, that amazingly small but nevertheless key cohort of voters is giving Mittens a second look to evaluate whether he is a safe and sober alternative to the devil they know. So it is not so much "mo" as a jump ball has been thrown into the air.
