The atmosphere that produces negative partisanship can fuel a paranoid loathing of the other party’s members. In its most concentrated form, it can drive people to aggressive violence. This is the sort of ill feeling that pundits invoke when they talk about a new civil war.
But that atmosphere also means that the two purportedly warring sides don’t command as much loyalty as those red/blue maps imply. Think back to last year’s election again. Both of the big parties were shaken by insurgent candidates, and one was unable to block the insurgent from winning. With both major parties picking their least popular nominees in recent memory, third-party and independent candidates had their strongest showings since Ross Perot’s campaigns. And this time, unlike in Perot’s day, the third-party vote wasn’t dominated by one popular personality.