I don’t know what the Hillary Clinton campaign is seeing in their polls, but one of her PACs is dumping 10½ million dollars into Pennsylvania.
The Republicans haven’t won a Presidential election in Pennsylvania since 1988.
Obviously, it is illegal for an independent PAC to coordinate, this has no relation to what the Clinton campaign is thinking (and according to Gilbert and Sullivan, married men never flirt).
If you believe that, then I have some swamp land in Florida you might be interested in purchasing.
One can look at this as the Clinton campaign taking nothing for granted, (glass half full) but if the past is precis, and panic mode does seem to be how the Clinton campaign operates, so I am inclined to see this glass as half empty.
Fivethirtyeight.com recently chided the Hillary campaign for *not* spending money in Pennsylvania: http://fivethirtyeight.com/features/the-clinton-campaign-seems-to-think-pennsylvania-is-in-the-bag/
Looks to me like the PAC is just filling in a gap.