In Pope Francis era, US candidates face new moral questions

The censure roared through the entire field of GOP presidential candidates, who were all pressed about the morality of their approach to immigrants in the country illegally, during a primary dominated by increasingly tough rhetoric that has emphasized border security.

Analysts say the pope's remarks should serve as a wake-up call for Republicans about how public discussion of religion and policy is broadening under this popular pope who, through his gestures and speeches, has put a greater emphasis on helping the vulnerable than on divisive social issues.

In 2004, Cardinal Raymond Burke, then the St. Louis archbishop, caused an uproar when said he would deny Communion to Democratic presidential nominee John Kerry, a Catholic who supports abortion rights.

Some bishops followed suit by telling Catholic politicians who support abortion rights not to present themselves for the sacrament.

Bush, one of the few GOP candidates proposing a path to legal status for people already in the U.S. illegally, said Thursday he supports "walls and fencing where it's appropriate."

Marco Rubio, another Catholic candidate for the GOP nomination, said he has "tremendous respect and admiration" for the pope, but he added, "There's no nation on Earth that's more compassionate on immigration than we are."