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.