By Anthony Salvanto, Jennifer De Pinto, Kabir Khanna and Fred Backus

The issue of family separation reveals deep divisions over not just immigration as an issue, but over views of immigrants, themselves -- and over what their treatment signals about America. The divisions hinge partly on partisanship but also heavily on views of President Trump, in particular. The president's strongest backers -- who call themselves "Trump supporter[s], period" -- are dramatically more favorable toward the separation policy, punishment for illegal entrants, more suspicious that most would-be immigrants are criminals, and far more skeptical that reports from detention centers are accurate than is the public as a whole. And the size of their ranks is largely unchanged over recent months.

Meanwhile the public overall disapproves of how the president has handled the separation matter this week, and many Democrats are skeptical that the separations will end, despite the executive order he signed last week.

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There is a notable difference of opinion over next steps toward reunifying the separated families. Republicans and President Trump's strongest backers saying it is not a high priority to re-unify them, while Democrats say that it is. Seventy-five percent of Democrats call it a high priority, compared to 23 percent of Republicans and just 16 percent of the president's strongest supporters. Women are more likely to call it a high priority than men.

A majority of Republicans also believes the conditions in the detention centers are probably better than portrayed in news reports. They are the only partisan segment that thinks so.

A large majority of Americans -- 72 percent - disapprove of family separation. Although Republicans split on that policy, generally – half support it, half oppose it -- Republicans do give the president high marks (81 percent favor) for his handling of the matter, overall.

Among the three-quarters of Americans overall who labeled the separation as a problem, 31 percent say the president has ended a problem he himself created; 27 percent (many of whom are Republicans) said he ended a problem he did not create; and 41 percent (largely Democrats) said he did not end the problem, despite having signed an executive order aiming to do so.

Views on what should happen to those trying to enter the country illegally vary with perceptions of why those immigrants are trying to enter. Republicans -- but in particular the president's strongest backers -- are the most likely to say that at least some of those trying to enter are criminals or gang members, and 30 percent say most of them are. By contrast, Democrats describe most immigrants as mostly people looking for jobs, or mostly trying to flee violence elsewhere.

Given a list of possible outcomes for families crossing the border, the largest preference Americans pick is releasing the family and returning them to their home country together (48 percent) rather than arresting the parents whether or not the family stays together.

More broadly, the poll asked whether those who enter the country illegally should generally be treated well, whether or not they were admitted, as an example of America's kindness to all -- or should be punished, as an example of America's toughness on illegal activity. Once again, there are wide partisan splits on the principle. Three-quarters of Democrats said they should be treated well, and three-quarters of Republicans said they should be punished.

Because his existing political base continues to support the president, even if they didn't like the separation policy, the poll suggests that any political fallout from the broadly unpopular policy -- if it emerges -- may be delayed or borne by his fellow Republicans in the fall. Asked whether the issue would change their midterms vote in November, half says it won't.

One-third of Americans and registered voters say the separation policy will be a very important matter in their congressional vote this fall. Of those who say it will change, more say it will make them vote Democratic than Republican. That gap is even larger among those who have never voted in a midterm before, meaning that if Democrats are to try to use discontent over this issue, it might be necessary for them to get new voters to the polls.

Those who approve of the president's handing of the separation matter tend to view the upcoming midterms as being about practical matters, that is, who will do the better job solving problems. Those who disapprove of his handling of family separation tend to say they see the midterms as about the values the country represents.

This CBS News 2018 Battleground Tracker was conducted by YouGov using a nationally representative sample of 2,063 U.S. adults between June 21-22, 2018. The margin of error (a 95 percent confidence interval) based upon the entire sample is approximately 2.6 percent.

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