Abramowitz: "Polarization is directly responsible for both the growing partisan divide among voters and the growing geographic divide in the nation. The growing consistency of party affiliation and ideology means that these two sets of attitudes increasingly reinforce one another, pushing voters in the same direction. Just as there are almost no liberal Republicans or conservative Democrats left in Congress, there are very few left in the electorate."

Fiorina: "Abramowitz throws out a potpourri of findings and assertions he regards as evidence of polarization. But on inspection, his claims are about sorting, not polarization…All the differences he cites between Democrats and Republicans are real, but they do not show a decline in the middle and an increase on the extremes; rather, they signify a sorting of liberal and conservatives into the “correct” parties as compared to a generation ago."