During a campaign event in Iowa over the weekend, Sen. Bernie Sanders (I–Vt.), a frontrunner for the Democratic Party's 2020 presidential nomination, rebuked an audience member who suggested the self-described democratic socialist supported open borders.

The audience member had begun to ask how Sanders would fund his vast social safety net if the U.S. were to adopt an open-borders immigration policy. Sanders interrupted him, countering, "Who do you think is suggesting opening the borders?"

The man responded by suggesting that Sanders had supported such a proposal, which is erroneous.

"I'm afraid you may be getting your information wrong," said Sanders. "That is not my view. I think what we need is comprehensive immigration reform. If your point is, open the borders, my god, there's a lot of poverty in this world and you're going to have people from all over the world, and I don't think that is something we can do at this point. Can't do it. So that is not my position."

Sen. Bernie Sanders campaigns in Oskaloosa, IA: "If you open the borders, there's a lot of poverty in this world, and you're going to have people from all over the world. And I don't think that's something that we can do at this point. Can't do it." pic.twitter.com/INF9GopzIe — The Hill (@thehill) April 7, 2019

This is nothing new for Sanders: In fact, during the 2016 campaign, he famously told Vox's Ezra Klein that open borders were a right wing "Koch brothers proposal" that would make "everybody in America poorer."

Generally speaking, this is not true—the U.S. economy would benefit massively from simply letting many more people enter the country legally. But Sanders probably realizes that the kind of comprehensive welfare state he would like to build—one that provides universal healthcare, minimum wage guarantees, and even free college tuition—will be more expensive and less politically popular if waves of immigrants qualified for it. Given a binary choice between liberating millions of people around the world from crippling poverty (while also lowering the costs of various goods and dramatically improving the U.S. economy) and making Medicare for All a reality, it's perfectly clear where Sanders stands.