A policy proposed by former President Trump to round up and deport undocumented immigrants — even if it requires using military-guarded encampments — has Americans divided, per a new survey.

Why it matters: The survey results come as Trump is promising to carry out mass deportations using a 226-year-old law that allows the federal government to detain "enemy aliens" in times of war.

By the numbers: 50% of Americans surveyed oppose setting up encampments for undocumented immigrants, while 47% favor the idea, according to the annual survey from the nonpartisan Public Religion Research Institute (PRRI), in partnership with the Brookings Institution.

Nearly 79% of Republicans favor putting undocumented immigrants in encampments, compared with 47% of independents and 22% of Democrats.
The vast majority of Americans who most trust far-right news (91%) or Fox News (82%) favor militarized encampments for undocumented immigrants, compared with 44% of Americans who do not watch TV news.

Zoom in: White evangelical Protestants (75%) are most likely to favor militarized encampments for undocumented immigrants, followed by 61% of white Catholics.

Among non-white Christians, around 47% of Hispanic Protestants, 42% of Black Protestants and 33% of Hispanic Catholics favor this policy.
39% of Jewish Americans and 32% of religiously unaffiliated Americans support the idea.

What they're saying: "I was pretty stunned at how many Americans, particularly Republicans and white evangelicals, supported this," Robert P. Jones, president and founder of PRRI, tells Axios.

Jones says the Alien Enemies Act was used just 80 years ago in World War II and there are people still alive who remember it.
"So it's not unimaginable that it can happen again. This is not just rhetoric here. I do think it's one of the more disturbing things that we found."

Background: Using the 1798 law is one of the steps Trump has mentioned as he talks about mass deportations and increasingly uses dark language about immigrants, calling them the "enemy from within" and falsely attacking their genes.

The intrigue: The same PRRI survey found that the country is growing more conservative on immigration policy.

52% of respondents said they favor allowing immigrants brought illegally to the U.S. as children to gain legal resident status — a 10-point decrease since the first time PRRI asked the question in 2018.
In addition, 51% of those surveyed support building a wall along the U.S. border with Mexico — a 10-point jump since 2016, when the question was first asked.

Yes, but: Many left-learning immigrant advocacy groups have been calling for a media blitz or change in polling questions to help Americans see how mass deportations would devastate families.

Valiente Action Fund, for example, tells Axios it found that hard negative ads against Trump, showing how his policies would separate families, swayed some Black and Latino male voters who were previously supporting hard immigration policies.
"We have to tell that story, and not let Trump define immigration for our country," Valiente Action Fund executive director Maria Rodriguez tells Axios.

Methodology: The American Values Survey was conducted online Aug. 16-Oct. 4. The poll is based on a representative sample of 5,027 adults (age 18 and older) living in all 50 states and the District of Columbia who are part of Ipsos' Knowledge Panel®.

The margin of sampling error is +/- 1.82 percentage points at the 95% confidence level, for results based on the entire sample.