(CNN) Ask people why they belong to their political party and they're almost as likely to tell you it's because the other party is so bad as they are to tell you they like something about the party they joined.

The trend is even more evident among independents. Republican and Democratic independent leaners will tell you that the harm of the opposing party's policies is the major reason they're leaning toward one party.

Americans don't like other parties so much that it's become core to their political identity.

These are the results of a recent poll by the Pew Research Center , which confirm the continuation of a several decades-long trend in political attitudes by partisans against each other.

The top "major reason" both Republicans (76%) and Democrats (72%) identify with their respective parties is that they think their own party's policies are good for the country.