Francis may be popular with the general public, but key Republican primary constituencies — hawks, climate-change skeptics and religious conservatives, including some Catholics, are wary of the pope’s progressivism. Some, pronouncing themselves “Republicans first and Catholics second,” even say they would look askance at a candidate perceived to hew too closely to the bishop of Rome. This internal conflict flips a familiar script, in which Democrats like John Kerry and Joe Biden were labeled “cafeteria Catholics” when their stances on social issues like abortion and gay ...