Politics isn't about who you love. It's about who you fear.
That's the upshot of a paper by political scientists Alan Abramowitz and Steven Webster that attempts to untangle a mystery about modern American politics: how can there be record levels of party loyalty and straight-ticket voting at the same time that fewer Americans than ever before are identifying as Republicans and Democrats?
To answer the question, Abramowitz and Webster test a host of political characteristics to see what best predicts party loyalty. The real key, they found, was fear of the other party: "Regardless of the strength of their attachment to their own party, the more voters dislike the opposing party, the greater the probability that they will vote consistently for their own party’s candidates."
It's worth saying that a bit more clearly: you're more likely to vote Democratic if you hate Republicans than if you love Democrats, and vice versa. What parties need to do to keep you loyal isn't make you inspired. Rather, they need to make you scared.