Pope Francis blesses faithful during his visit to the Morelia Cathedral in Mexico's Michoacan state, Feb. 16, 2016.
Pope Francis blesses faithful during his visit to the Morelia Cathedral in Mexico's Michoacan state, Feb. 16, 2016.

WASHINGTON - In the midst of a U.S. presidential campaign that has already defied precedent and expectations, a sharp exchange on immigration between Republican front-runner Donald Trump and the head of the Roman Catholic Church, Pope Francis, is now dominating the conversation.

On a flight back to Rome after visiting Mexico, a reporter asked the pope about Trump’s plans to build a massive wall on the U.S. border with Mexico.  Pope Francis said: “A person who thinks only about building walls, wherever they may be, and not building bridges, is not Christian.”

At a campaign rally in South Carolina Thursday, billionaire Donald Trump responded swiftly, saying the pope questioning his faith is “disgraceful.”  At a nationally televised Republican town hall Thursday evening on CNN, Trump appeared to soften his stance. He said he has a lot of respect for the pope, that Pope Francis has a lot of personality, and that he may have been given wrong information about his border plan.

The clash comes just 2 days ahead of the South Carolina Republican primary, where recent polls show Trump with a big lead over the rest of the Republican field.  The other Republican candidates responded cautiously when asked about the Trump-Pope exchange.

Republican presidential candidate Donald Trump spe
Republican presidential candidate Donald Trump speaks during a campaign stop, Feb. 16, 2016, in Beaufort, S.C.

‘That’s between Donald and the pope’

At the same town hall, Former Florida governor Jeb Bush said the pope is an inspirational leader of his church, but he does not think it is appropriate to question Trump’s Christian faith.   Ohio Governor John Kasich, who is also Catholic, said: “Put me down in the pro-pope column.  He has opened that walls and doors of the Church to a lot of people who don’t understand it.”

Earlier Thursday, Florida Senator Marco Rubio, who is also Catholic, also praised the pope, calling him “the holy father.”  But he said the U.S. has a right to keep people safe by enforcing immigration laws.  Texas Senator Ted Cruz, who has clashed sharply with Trump on a number of issues, did not attack him on this, saying:  “Listen, that’s between Donald and the pope.  I’m not going to get in the middle of that.”

Candidate and retired neurosurgeon Ben Carson said the clash between the pope and Trump would be hilarious if it weren’t so sad.  But he also defended the tough border security stance: “enforcing our immigration laws is not in contradiction with love and kindness.”

Pope Francis speaks to journalists aboard his plan
Pope Francis speaks to journalists aboard his plane during his flight from Ciudad Juarez, Mexico, to Rome, Italy, Feb. 17, 2016.

‘Trump has no positive plan’

Father Thomas Reese is a Jesuit priest and a senior analyst for the National Catholic Reporter. In an interview with VOA Thursday, Reese strongly agreed with Pope Francis’ stance on immigration, saying  it is not right to fence off human beings.  Reese blasted Trump’s remarks on immigration and border security: “He has no positive plan to deal with immigrants.  He just wants to round up any illegal immigrants in the U.S. and ship them out. I mean that is 10 million people.” 

Trump also said that if Islamic State terrorists attack the Vatican, the pope would hope and pray that he is president.  Reese said the pope is not afraid of being killed, and that lots of popes throughout history have been killed for their faith.  Reese said he does not believe the clash will have a lasting impact on the race, though he did say he believes that most Catholic Republicans “are not buying” Trump’s candidacy.  He also said Catholics are known for overwhelmingly picking the winner in presidential races.

Catholics make up about 25 percent of the U.S. electorate, but are not strongly represented in the next primary state, South Carolina.  Nationwide, Catholics have been swing voters in recent elections, switching from Republicans to Democrats.  A CNN poll from last September showed that 63 percent of Americans have a favorable opinion of Pope Francis.

The pope visited the United States last September and became the first pope in history to address a joint meeting of Congress.  Concern for immigrants and the poor was at the heart of his message during that trip. Polls show that immigration is also a major issue for Hispanic Catholics in the United States.

WATCH:  Walls explainer