Interesting stuff from 538 showing that there are only eleven realistic battlegrounds based on the polling data (flawed, subjective, and not a real final predictor of anything more than the current psyche of America). It states that the eleven states are technically McCain's to lose, but these states are definitely buckling under the momentum from the Obama-DNC machine v.2008.
I assume first, Obama wins these eleven plus those leaning, trending, or already in his court; then I look only at the historical election trends; and finally the eleven plus those already in McCains court.
407 – 131 Obama: Democrats Best Case;
289 - 249 Obama: Trend Predictor using this data, and giving FL to McCain (which seems could trend either way);
286 - 252 McCain: Republicans Best Case;
Conclusion:
If case #2 is the average of what can be more or less expected in november then Republicans have a natural 15% deficit to overcome. That said in terms of the popular vote, McCain would need to be polling to win by no less than 3% in order to feel safe... or safer.
Its a tall task as that would mean he has to make up a 7-point gap just to appear competitive... let alone be much for anything approaching inevitable.
At this time, it is clearly Obama's to lose... a truly ugly situation for the future of the republicans.