I think the issue is that McCain is running out of funds to be in all places where he is being challenged. So IMO I think he is having to spend more money in states he thought would have stayed red without having to spend a dime which he is now having to defend. And that means that he has to let go of lost causes like Michigan (and possibly PA) and concentrate his dwindling funds defending red states. But that's JMHO.
"When fascism comes to America, it will be wrapped in the flag and carrying a cross." - Sinclair Lewis
"Those Who Would Sacrifice Liberty for Security Deserve Neither." -Benjamin Franklin