PA-15: Rep. Charlie Dent (R) to retire

[Southern Senator North Carolina Yankee]

Oof! He was the GOP's only hope of ever winning another senate seat in PA.

If he could even win the primary (I doubt he would), I bet a lot of conservatives, especially those who are pro-lifers and/or Trumpists, would either stay home, vote third party, or even defect to Casey. This isn't Hotelling's model, where you race to the center to win, winning these days is really about firing up the base (and keeping them on your side).

Indeed! That's why Romney did so well when he appealed to the base on immigration, taxes, guns, and gay marriage.

Romney pursued too narrow of a base in terms of the electoral college.