Mitt Romney has one clear route to victory on Nov. 6: In addition to winning all the states we know he will win, he has to capture Florida, Virginia, Ohio and at least one of five other swing states.
It's very possible Romney will win more than that. Our model of presidential elections, for example, has him with a 17.2 percent chance of winning Pennsylvania. Were he to manage that, however, it would almost certainly be part of a national landslide in his favor that includes most of the swing states. While I'm sure the Romney campaign would be delighted to win Pennsylvania, if it manages that it will be because Romney won far more than the 270 electoral votes he needed.
Here is where things stand today:
There are six additional states in each camp that have at least an 80 percent chance of going for the leading candidate.
In those 12 heavily leaning states, it is very possible that Romney or Obama can pick off one. It is nearly impossible that one of these states will decide the election.
This leaves eight states, worth 95 electoral votes, in play. Without those states, Obama has 237 electoral votes to Romney's 206 electoral votes. A candidate needs 270 votes for victory, so Obama needs 33 more and Romney needs 64 more to win.
If Romney can capture Florida, Virginia, and Ohio—the three swing states he's most likely to win—he will come within four votes of the magic number. At that point, he would need any one of the other swing states: New Hampshire and Iowa are the most likely, both near 55 percent for Obama. While Romney's running mate, Paul Ryan, hails from Wisconsin, the polls there have consistently favored Obama by about 4 percentage points. Data from the past 10 elections has demonstrated again and again that vice-presidential home state bumps are negligible.
Can he do it? Follow along in real time with PredictWise.com.