Presidential candidate Bernie Sanders took a surprising line on immigration in a recent interview, denouncing higher immigration levels as a right-wing “Koch brothers proposal.”

Sanders was being interviewed by Ezra Klein of Vox, who pointed out that Sanders’ self-proclaimed socialist beliefs typically entailed taking a more international view of politics. The implications of that point of view, Klein suggested, include “things like sharply raising the level of immigration we permit, even up to a level of open borders.”

Absolutely not, Sanders replied.

“Open borders? No, that’s a Koch brothers proposal,” he said. “That’s a right-wing proposal, which says essentially there is no United States… What right-wing people in this country would love is an open-border policy.”

Klein countered by saying heavier immigration would allow the global poor to become richer, but Sanders said that could only come at the expense of existing American workers.

“You know what youth unemployment is in the United States of America today?” he said. “If you’re a white high school graduate, it’s 33 percent, Hispanic 36 percent, African American 51 percent. You think we should open the borders and bring in a lot of low-wage workers, or do you think maybe we should try to get jobs for those kids?”

“I think from a moral responsibility we’ve got to work with the rest of the industrialized world to address the problems of international poverty, but you don’t do that by making people in this country even poorer,” he continued.

Sanders’ frank response puts the populist left-wing candidate oddly close to the rhetoric of Donald Trump, who has surged in the Republican primary contest in large part thanks to his severe denunciations of illegal immigration.

It also puts distance, at least rhetorically, between him and Hillary Clinton, who has distinguished herself on immigration mostly by promising to go further than President Obama on the issue.

Sanders has shown signs in the past that he is less pro-immigration than some of his Democratic colleagues. In 2007, he was a major Democratic opponent of George W. Bush’s immigration reform bill, arguing that welcoming more guest workers would drive down wages for American workers.

Since launching his long-shot effort against Clinton in the spring, Sanders has mostly avoided the immigration issue, though he said in a June speech he supports immigration reform that provides a path to citizenship for current illegal immigrants.

Read the full interview here.

Follow Blake on Twitter