Don’t write off PA. IIRC the registration over the last four years went Trump’s way. Enough to cover the gap in 2012. I don’t recall the numbers but it looked like Trump had PA by about 100,000.
PA has been weak for the GOP in the mid-terms. The GOP governor was almost the only Repub who lost anywhere in the 2014 mid-terms. Toomey’s Senate win in 2010 was a 2% spread, a close margin in a huge GOP election year.