|A prediction of the Electoral College map, July 28, 2012.|
Call this the Gary Johnson effect.
Johnson's ballot access will shave off enough votes from Romney in New Hampshire and New Mexico to hand the election to Obama. However, the drawback of assuming that statement is that Johnson's current polling shows he is drawing from both sides of the fence (folks like me, for example, who would be more likely to vote for a true populist Democrat like a 1990s Jerry Brown or a 1980s Fritz Hollings who won't go near Obama or Romney so ...). Not unlike the false presumptions about Ralph Nader in 2000, Johnson's supporters are all over the map politically.
The other piece to the puzzle is that we don't know who Romney's running mate is and that could influence voters in one of the states. A Kelly Ayotte on the ticket pulls NH away from Obama as would Johnson not making the ballot here (unlikely). It would also draw some women away from Obama. Someone like Wisconsin Gov. Scott Walker on the ticket - very unlikely but who knows - throws that state into the Romney tally and that would ensure a victory for Mitt.
We also don't know where the Green Party's Jill Stein factors into the scheme of things. She has matching funds - meaning she'll have advertising, not unlike Nader. She could shave off enough votes for Obama in a place like Massachusetts to throw those EC votes to Romney (he is still popular with indies there, despite what the Globe says).
You too can have fun with the map here: http://www.cnn.com/election/2012/ecalculator#