Bernie Sanders, the Vermont senator making a run for the Democratic presidential nomination, has always had a rather complex relationship with immigration.

The self-described democratic socialist voted for the DREAM Act, supports a pathway to citizenship, and has spoken out on the travails faced by immigrant and migrant worker families. But he also raised objections to comprehensive immigration reform in 2007, mainly due to the various guest worker policies it included. So Americans who prioritize immigration as an issue view Sanders with some trepidation, and the senator has been modifying his message to assuage them.

Sanders' conflicted position came up again in an extensive interview Vox released on Tuesday, when Ezra Klein pressed him on the idea of drastically raising immigration levels (or even opening American borders wholesale) as a way to combat global poverty.

Sanders has a reputation for cantankerousness, and he didn't disappoint: "No, that's a Koch brothers proposal," he said. "It would make everybody in America poorer."

We need to make sure "people in poor countries have decent-paying jobs, have education, have health care, have nutrition for their people," Sanders continued. But we shouldn't do it "by lowering the standard of American workers, which has already gone down very significantly."

This presents the immigration question as an ethical dilemma. On the one hand, immigrants and people everywhere deserve aid and equal dignity. And the immigration status quo is manifestly unjust. On the other hand, Sanders understandably feels his first obligation is to care for the interests of the people who are already in his constituency — especially the ones of less means — and worries that too much immigration would threaten their already precarious wages and jobs.

There's a plausible economic story one can tell in which big influxes of immigrants drive down American wages, especially at the low end. But evidence that story is actually occurring has been scant. (Granted, throwing America's borders wide open would lead to far greater levels of immigration than anyone's had a chance to study.)

But more deeply, is there an inevitable connection between higher immigration and depressed living standards? Or can the dynamic be avoided?

Elsewhere in the Vox interview, Sanders inadvertently hit on evidence it can, when he observed that culinary and hotel workers in Las Vegas have secured high wages and health benefits. Sanders' point was simply that service sector jobs can be made into highly compensated jobs. But those are also the types of workers immigrants supposedly compete with. And the way they succeeded in Las Vegas suggests how wages and jobs for more vulnerable Americans could be boosted even if America was absorbing way more immigrants.

What happened in Las Vegas was that the union movement cornered the market on those particular forms of labor. Unions provide workers with bargaining power: Employers must give employees a better deal — in terms of wages and benefits and more — or the employers can’t get business done. And Sanders, being a lefty, is all about strengthening unions. So the first point to make is that every immigrant that enters America is a new potential union member, who can add to the groups' numbers and organizational clout.

But more fundamentally, there is a whole host of policy options beyond unions that could also grant workers more bargaining power — mainly by driving the country towards full employment. Worries that immigration will up competition for jobs and depress wages implicitly assume that the supply of jobs is scarce compared to the supply of labor. But the right macroeconomic policies can help ensure the supply of jobs outpaces labor as often as possible.

The thing to remember is that every person who comes to the United States is not simply a body who can take a job. They also bring all the needs — for food, for shelter, for fuel, for education, for health care, for entertainment, and more — that create the raw demand out of which new jobs are fashioned. If policy properly takes advantage of that demand, then we can keep employment up — and keep employers terrified of losing workers to better-paying jobs — even as we absorb more immigrants.

More to the point, a lot of those policies are ones Bernie Sanders already supports. Start with single-payer health care. If the government provides affordable and universal health care, that employs people in the health care industry, but more importantly it means everyone else doesn't have to pour their own income into unexpected health problems or emergencies. Instead, that money can go into buying goods and services that will employ other workers. It would also remove a big source of desperation in many Americans' lives, again giving them more leverage to demand better compensation.

The same goes for a more expanded safety net in general. Government aid helps people acquire food and shelter, and get through periods of unemployment, by buying those same goods and services. In fact, Sanders should take a cue from the very Nordic economies he points to as exemplars, and push for the government to provide a universal set of benefits that applies to everyone in positions of vulnerability.

Also note that as long as employment is high and immigrants can move into jobs, we'll all be generating the income that supplies the government revenue to fund these sorts of programs.

Finally, Sanders should start making monetary policy a key issue. In setting that policy, the Federal Reserve must always balance the possibility of full employment against the possibility of inflation. By insisting the Fed set a greater priority on full employment — or even by radically reforming monetary policy — Sanders could help correct one of the biggest long-term failures in American politics.

Sanders is right to be skeptical of mediocre guest worker programs. They tie immigrants to particular jobs, preventing the kind of free labor market competition that full employment requires. We should keep immigration reform big and simple: legalize everyone already here, vastly simplify the process, lower the costs of becoming a citizen, and be far more merciful with deportations.

But for Sanders such a move would only be a "Koch proposal" in a "Koch world," characterized by the overall package of policies the Kochs support. In a Bernie Sanders world, open borders could be something else entirely: a way to make the United States a haven both for workers and for those tired, poor, huddled masses.