Sen. Bernie Sanders’ (I-VT) presidential campaign has been accused of retaliating against staffers for unionizing, as new details of the federal labor complaint made on July 19 continue to surface.

An unnamed individual filed the complaint to the National Labor Relations Board on July 19 and alleged five potential violations, including retaliation, discipline, discharge, interrogation, and repudiation. Details of the complaint against the Bernie Sanders campaign have been scarce, but Bloomberg Law obtained a copy of the charge, which details the allegations further.

While anyone can file a charge, the individual claims to be a staffer, who accused the Sanders campaign of retaliating after he or she “organized the bargaining unit.” Earlier this year, Sanders’ campaign became “the first presidential campaign in U.S. history to have a unionized workforce.”

The complaint alleges that the campaign terminated three employees “because the employees joined or supported a labor organization and in order to discourage union activities and/or membership.” It further states that the campaign disciplined or retaliated against three employees “because the employees engaged in protected concerted activities by, inter alia, discussion wages, hours, or other terms and conditions of employment and in order to discourage employees from engaging in protected concerted activities.”

Bloomberg Law added:

The unknown filer alleged that the campaign “failed to notify us upon hire that we had a” collective bargaining agreement and “maintained that we were ‘at-will.’” At-will workers generally can be fired at any time and for any reason the employer deems appropriate. The charge alleges that management promised “some employees housing, and not others,” despite that paid housing and expenses are required under the collective bargaining agreement. The Sanders campaign also broke the terms of its collective bargaining agreement by making staff work additional days and failing to provide days off, the charge alleges. Many of the allegations appear to have occurred at least a month prior to the recent compromise reached between campaign workers and management that reduced the hours worked. The timing of other allegations was redacted.

Sanders told the Des Moines Register last week that he was bothered that employees were exposing the tense negotiations, calling it “not acceptable” and “improper,” despite the fact that he has considered himself a long-held champion of the labor movement.

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

Sanders’ remarks followed complaints from unsettled employees, who accused his campaign of paying “poverty wages,” particularly to field organizers. Union members prepared a letter to Sanders’ campaign manager Faiz Shakir, which stated that field organizers “cannot be expected to build the largest grassroots organizing program in American history while making poverty wages.”

“Given our campaign’s commitment to fighting for a living wage of at least $15.00 an hour, we believe it is only fair that the campaign would carry through this commitment to its own field team,” the letter continued.

Sanders initially said that he would ensure that staffers got $15 an hour by limiting hours:

Sanders said field organizers, who are the lowest-ranking members of a presidential campaign and are typically in their 20s, make $36,000 a year with 100% employer-paid health care, as well as paid vacation and sick leave. For a staffer working 40 hours a week, that comes out to about $17 an hour. But 40-hour workweeks on presidential campaigns are rare. Sanders said the campaign will limit the number of hours staffers work to 42 or 43 each week to ensure they’re making the equivalent of $15 an hour.

However, Sanders told CNN this week that his campaign made an offer, which was accepted.

“We made an offer which would have addressed that problem several months ago; it was rejected,” Sanders told CNN. “We underwent negotiations. It has now, the offer, it has been accepted.”

“Board investigators will look into the charge to determine whether it warrants a formal, government-backed complaint or should be dismissed,” Bloomberg Law reported.