Ronaldo Cantú is originally from Texas, and is now a junior at American University in Washington, D.C. But I caught up with him a few weeks ago in Berlin, New Hampshire, where he was helping set up tables and chairs in a packed catering hall, before Sen. Bernie Sanders was scheduled to speak.

Cantu is spending his summer in New Hampshire, working as an intern on Sanders’ presidential campaign. What made it possible, he said, is the $15 an hour wage that came with the job.

“For me personally, I purposefully tried to target the internships that were paid. Just because for myself, I’m a low-income student, my family is middle to low income, so I really cannot afford to do an unpaid internship,” Cantú said.

As the New Hampshire presidential primary heats up, situations like Cantú’s are becoming increasingly common.

This election cycle, more Democratic candidates than ever have pledged to pay interns. At least nine candidates have said that they offer paid internship or fellowship programs, including Joe Biden, Cory Booker, and Elizabeth Warren. It can be a significant expense, especially for large campaigns that rely on small armies of interns to help with data entry, event organizing,phone banking and door-knocking.

The shift to more paid work comes during a campaign in which issues like economic inequality and raising the minimum wage are key issues.