“…Because it is hard to persuade people who think like this to switch sides, electoral strategists argue that chasing swing voters is pointless. The easiest extra votes come from the 40% of the electorate who typically stay at home in a presidential poll. Each side therefore concentrates on stirring up people who support it but might not vote. That raises the anger to a new pitch.”

“…Despair over Mr Trump has reached such an intensity among some Republicans that the usual rules about there being no swing voters may no longer apply.”

http://www.economist.com/news/leaders/21693924-prospect-trump-v-clinton-grim-look-carefully-and-2016-offers-faint-promise?fsrc=scn/tw/te/pe/ed/battlelines