Sen. Bernie Sanders (I-VT) told The Des Moines Register he was “very proud” to lead the first major presidential campaign with unionized workers, but also “bothered” that news of the internal strife had spilled into the media.

The self-described socialist candidate said junior field organizers earn roughly $36,000 per year in salary, with employer-paid health care and sick leave. But he acknowledged that their salary can effectively dip below $15 per hour if staffers work much more than 40 hours per week, which is common on presidential campaigns.

The solution is to “limit the number of hours staffers work to 42 or 43 each week to ensure they’re making the equivalent of $15 an hour,” he told the Register’s Brianne Pfannenstiel.

“It does bother me that people are going outside of the process and going to the media,” Sanders added. “That is really not acceptable. It is really not what labor negotiations are about, and it’s improper.”

He went on to say that the union contract “not only provides pay of at least $15 an hour, it also provides, I think, the best health care benefits that any employer can provide for our field organizers.”