The nation's Catholic bishops are unequivocal in their support for immigration reform that would include a so-called pathway to citizenship for the estimated 11 million immigrants who are in the United States without legal documents.

But while the bishops frame their position as a prophetic defense of human rights, immigration remains a volatile and controversial political issue that divides many Americans, including lay Catholics.

"This has obviously touched a nerve with the various presidential candidates, particularly on the Republican side," said James F. Driscoll, executive director of the Massachusetts Catholic Conference.

"I expect immigration to be one of the major issues leading into the elections," Driscoll said.

Donald Trump, the outspoken businessman currently leading the field of Republican presidential candidates, has tapped into widespread voter frustration. In stark contrast to the bishops, Trump calls for the immediate deportation of all illegal immigrants, claiming they are responsible for many violent crimes.

Trump proposes ending birthright citizenship for children born in the U.S., and wants to not only increase border security, but even require the Mexican government to build a wall along the U.S. border.

"Real immigration reform puts the needs of working people first, not wealthy donors. We are the only country in the world whose immigration system puts the needs of other nations ahead of our own. That must change," Trump writes in a policy paper published on his campaign website.

Trump's rhetoric and immigration proposals have drawn criticism from other Republican candidates and may be alienating Latino voters. A recent Gallup poll found that Latinos were more likely to say they dislike Trump than like him by a 51-point margin.

However, Peter Skerry, a Boston College political science professor whose research focuses on immigration, social policy, racial and ethnic politics, said that Trump has scored points by attacking political elites for double-talk and avoiding tough decisions on issues like immigration.

"In one sense, he's right," Skerry said. "Immigration has been an issue dominated and manipulated by our political elites, conservatives and liberals, for a long time. We're always talking about things that are on the margins and that get people excited, jazzed up or frustrated."

From the bishops' perspectives, human suffering is a real issue to be confronted when discussing immigration.

The U.S. Conference of Catholic Bishops, joined by a growing body of Church teaching that includes papal encyclicals, episcopal statements and pastoral letters, emphasizes the Biblical command to treat the stranger as one would treat Christ. With that in mind, the bishops support an immigration system that would allow undocumented migrants to become legal citizens. The bishops also call for reforms to reunite families more quickly and to allow low-skilled migrant workers to enter the U.S. legally as needed labor.

Following President Barack Obama's November 2014 announcement that his administration would not deport millions of undocumented immigrants who met specific requirements, Cardinal Seán P. O'Malley said in a written statement that immigration "is not primarily a political problem, but rather a deeply human and profoundly moral challenge facing our nation."

"We leave the constitutional and political issues to those entrusted by office; only they can provide a comprehensive resolution," Cardinal O'Malley said. "Our primary focus is on the undocumented families, the men, the women, and children now stranded in a legal void, living on the margins of our society, in fear of being discovered and deported -- either individually or as families."

A Catholic approach to immigration, Driscoll said, is to welcome the immigrant.

"We're saying that an immigrant, even an undocumented immigrant, should have a path to citizenship so they can contribute to society," Driscoll said.

But the broad principle of being a "welcoming nation" gets complicated at the policy level, where tough decisions are made. Skerry describes the popular "nation of immigrants" tagline as "boilerplate" that fails to solve difficult problems.

"Generally, this issue gets caught up in a Statue of Liberty haze that doesn't help our thinking. It's a way for politicians to avoid the tough questions," Skerry said.

C.J. Doyle, executive director of the Catholic Action League of Massachusetts, also noted that Catholic social teaching, affirmed by Doctors of the Church such as St. Thomas Aquinas, has held that governments have the responsibility to protect their citizens, even restricting immigration if necessary.

"Immigration policy is a matter of prudential decision making, for which the bishops have no specific competence," Doyle said, adding that Americans have rational and well-founded concerns about how illegal immigration impacts the sovereignty, demography, culture, finances and national security of the United States.

The bishops' immigration position, Doyle said, "seems to be a mixture of pacifism, sentimentalism and political correctness masquerading as Christian charity."

"The bishops say this is part of their prophetic role," Skerry added. "But in terms of public policy, their prophetic role only gets them so far."

But in arguing that the consensus across party lines and political affiliations agrees that the nation's immigration system is "broken," Cardinal O'Malley said in November that the Catholic Church in the United States will continue to be "deeply committed to a long-term, fair and effective reform" of the immigration laws.

Cardinal O'Malley added that the bishops have also been given new inspiration and leadership by Pope Francis, who has sought to call the world's attention to the plight of immigrants.

"From a Catholic perspective," Driscoll said, "The goal of helping 11 million undocumented people to a path of citizenship should be the goal of immigration, and how we can do that safely and securely, while being a welcoming nation."