Can Clinton-Kaine Bring Catholic Voters Back to the Democrats?

If there is one constant in this unconventional presidential campaign it is the unpredictability — and importance — of the Catholic vote.

Once a reliably Democratic cohort, Catholics have in recent decades swung back and forth between the two parties. And because they represent more than a fifth of all voters, and are concentrated in key Midwestern swing states, the candidate with the most Catholic support has wound up winning the popular vote.