COLUMBUS, Ohio (WCMH) — The Ohio Federation of Teachers accuses a Columbus charter school of anti-union activity in an Unfair Labor Practices charge and a complaint filed with the U.S. Department of Labor.

NBC4 first reported on efforts to form a teacher’s union at KIPP Columbus in December, after teachers say 78% of the school’s employees signed cards signaling a desire for a union vote. In the ULP charge submitted to the National Labor Relations Board last November, employees said the school has “interfered with, restrained, and coerced employees in the exercise of their rights guaranteed in Section 7 of the National Labor Relations Act.”

“Specifically, employees have been required to attend mandatory meetings in which the employer both through company employed upper level management and outside consultants, dissuaded employees from exercising their protected Section 7 activities through implicit threats” the charge read.

“We have organized nine charter schools in Ohio so far. And we have not seen union busting as aggressive as this,” said Ohio Federation of Teachers President Melissa Cropper.

Andrew Mensah, a high school math teacher and football coach at KIPP Columbus, is part of the 12-member organizing committee for the union vote, which has not happened yet.

“The overall goal is to increase student achievement,” Mensah said. “A lot of us believe that best happens when you have teachers that are there year after year.”

Mensah said he hopes a union can address attrition issues at KIPP Columbus, where his 11 years of employment make him the longest-tenured teacher at the school. He said he looked forward to engaging in meaningful conversations with administration and consultants about unionizing, but that has not happened.

“We get to school around 7:45, and then at 7:55 you get an email that you’re going to a (mandatory) meeting for anywhere from 30 minutes to an hour and 45 minutes, which, as a teacher, is a significant portion of the day,” Mensah said. “(The meetings) turned out to be a lot of one-sided conversations. A lot of, ‘No, this is the way it is.'”

Mensah said a consultant conducting the meetings would not disclose her last name, citing safety reasons.

According to the complaint the federation emailed to the Office of Labor Management Standards, the consultant had not filed required paperwork and was believed to be using an alias.

The Labor Management Reporting and Disclosure Act requires labor consultants to provide certain information on what’s known as a Form LM-20.

“Employees have the right to know who is talking to them about the union, so they can determine for themselves whether this person has a bias or not, and also deserves to know how much their employer is paying for those services,” said Cropper. “And in this case, because it gets public dollars — public taxpayers dollars — so the public also has a right to know who this person is who’s coming into the school district to have these conversations and how much of their taxpayer dollars being used for these conversations.”

As a charter school, referred to in Ohio as a community school, KIPP Columbus is run by a private company but is funded almost entirely by public money, coming from tax dollars and lottery profits.

Asked in an email how much money the school spent on the labor consulting, Superintendent Ciji Pittman did not answer.

“KIPP Columbus respects the rights of our teammates to organize; and that right is equally held with the right to not organize.“ KIPP wrote back to NBC4. “We encourage all of our colleagues to consider all relevant information — from multiple sources — about what it would mean to join a union and what the collective bargaining process entails. Many of our colleagues have asked questions about these topics and we have worked diligently to ensure those questions are answered promptly.”

KIPP has sent letters to staff and families regarding union talks and posted flyers in employee breakrooms.

“We respect our colleagues’ rights to consider joining OFT but we do not believe this will have a positive impact on our school community,” said one of the letters from Pittman, dated December 5.

The literature says unionizing would cause teachers to “give up (their) seat at the table for a third party” and create “risks to pay, benefits and more.”

“If we, as teachers, do have a seat at the table, we’re not invited into the room to take it and to speak from it,” Mensah said.