Using NBC Political Director Chuck Todd's latest map of "safe" states (above) for each candidate showing only seven swing states remaining... Florida, Ohio, Wisconsin, Colorado, New Hampshire, Iowa, and Virginia... I stayed up late last night compiling this simple "Victory Matrix", a brief table showing the swing states each candidate needs to reach the minimum 270 Electoral Votes necessary to win.
Assuming a starting point of 243 bankable EV's for Obama and 206 EV's for Romney, here are the fewest swing states each candidate needs to reach the 270 vote threshold:
As you can see, if President Obama wins Florida, it's game over for Romney. The President can lose every other swing state and still break 270. So Florida is a "must win" for Romney.
Obama also has many more paths to victory. If he loses Florida, he still has EIGHT more paths to victory. In fact, he can lose both Florida AND Ohio and still has FOUR paths to victory. There is no absolute "must win" state for President Obama.
Governor Romney on the other hand has a much steeper hill to climb, with far fewer paths to victory with (as noted) Florida being a "must win" for him or it is all over. Mitt has just five paths to victory (sans an upset in a "safely blue" state not listed here), all of which require winning at least four swing states, with "Iowa" and NH being the states he least needs to still win. So if President Obama is the first to win four, likewise the race should technically be over.
Three of Romney's five paths require winning Ohio, while four require winning Virgina. So if he loses one, he MUST win the other to stay alive. Based on the latest polls, Romney has a much better chance of winning Virgina than Ohio (though he trails in both), so while everyone else will be watching Ohio, I will be watching Virgina. Romney has but one path to victory if he loses Virgina, so if Obama wins that, I predict the race to be over rather early.
You can use this table like a scorecard. Let's just hope the race isn't close enough to steal, with no surprises, and we're all in bed by a decent hour.