Fundraising phone calls are the bane of many campaigns’ (and voters’) existence. When it comes to wooing the wealthiest donors, elected officials typically complain about the amount of time spent soliciting funds. “There have been decades and decades of members of Congress losing their lives to ‘dialing for dollars,’ ” Ciara Torres-Spelliscy, a law professor at Stetson University who studies political fundraising, told Marketplace in March.

At lower donation levels it’s an equally thankless (but less lucrative) job, full of hang-ups and angry voters wondering how a campaign got their number and why they’re being bothered in the middle of dinner.

Unfortunately, the prisoners contracted to work on Bloomberg’s presidential campaign had no choice, as The Intercept reported Tuesday. Michael Bloomberg 2020 hired ProCom, a New Jersey-based call center company that owns centers in New Jersey and Oklahoma; two of the Oklahoma call centers operate out of state prisons. “In at least one of the two prisons,” The Intercept’s John Washington reports, “incarcerated people were contracted to make calls on behalf of the Bloomberg campaign.”

Washington continues:

According to a source, who asked for anonymity for fear of retribution, people incarcerated at the Dr. Eddie Warrior Correctional Center, a minimum-security women’s prison with a capacity of more than 900, were making calls to California on behalf of Bloomberg. The people were required to end their calls by disclosing that the calls were paid for by the Bloomberg campaign. They did not disclose, however, that they were calling from behind bars.

Michael Bloomberg is worth $55.9 billion, according to the Forbes real-time wealth tracker. John Scallan, a founder of ProCom, told The Intercept that his company pays $7.25 per hour, Oklahoma’s minimum wage, to the state’s Department of Corrections, which then pays the prisoners. The Intercept found conflicting information on exactly how much of that money gets to prisoners. The Department of Corrections website says the maximum monthly salary prisoners can receive is $20. Scallan claims ProCom workers earn more.

According to a 2017 study from the Prison Policy Institute, Oklahoma prisons working in nonstate-owned industries typically make 54 cents an hour, at most.

The news comes just as Bloomberg attempts to reckon with his criminal justice policies as mayor of New York City. During his tenure as mayor, from 2002 to 2013, and for years afterward, he was a vocal supporter of stop-and-frisk, a policing strategy that gives wide latitude for officers to stop anyone they deem suspicious—and one that disproportionately targeted black and Latino people. This November Bloomberg reversed his position, telling the crowd at a predominantly black church, “I was wrong. And I’m sorry.” The New York Times called the apology “almost unheard-of,” and “a remarkable concession by a 77-year-old billionaire not known for self-doubt.”

The campaign said it has ended the relationship with ProCom. “We didn’t know about this and we never would have allowed it if we had,” Bloomberg spokesperson Julie Wood told The Intercept, which also reported that “[the campaign] said it has asked vendors to do a better job of vetting subcontractors in the future.”

Later that day, Bloomberg posted a longer apology to his Twitter account: