Shaken by the retirement of its disgraced CEO Michael Milkie and worried by an increasingly hostile political climate, the Noble Network of Charter Schools sought to reassure bondholders on Thursday.

In a 25-minute phone call, CEO Constance Jones said that Noble had weathered uncertainty in the past and would continue to do so, even with the recent election of J.B. Pritzker as governor, who has supported a moratorium on new charter schools.

“We are not naive to the fact that we do operate in an environment where politics could impact our funding, freedoms and ability to operate,” Jones said. “My invitation to whoever is elected to office always has been, regardless of what your opinion on Noble has been, come to our campuses.”

The non-profit Noble, Chicago’s biggest charter network, operates 18 schools for more than 13,000 students. It receives about 90 percent of its revenue from federal, state and city sources. The rest comes from donors, including some of the wealthiest Chicagoans, and other sources. Bondholders help fund construction, which is not publicly funded for charters.

One of the Noble campuses, in the Hermosa neighborhood, is named after the governor-elect’s sister, Penny Pritzker, the former U.S. commerce secretary under President Barack Obama.

Charter schools are public schools, but run by independent boards and freed from many state rules governing education.

After years of expansion, Noble now faces uncertainty and challenges in several areas. Founder Milkie is stepping down next month for inappropriate conduct with alumni. Noble’s charter is up for renewal, with Chicago Public Schools scheduled to announce its decision next week. And restive teachers are seeking to unionize.

On top of that, political winds may shift. The state’s newly elected Democratic governor has pledged to place a moratorium on charter school expansion. And in the upcoming mayoral election, Chicago could choose a chief — who effectively oversees the schools — unfriendly to charters.

During Thursday’s call, Jeff Russ from Wells Fargo asked about accountability policies, rules on student discipline, and limits on charter expansion.

Russ also asked whether the network would consider creating protections for whistleblowers, to allow staff to safely speak out about wrongdoing.

Jones, who stepped up to CEO after being president of the network, said a protective policy was under consideration but stopped short of promising to institute it. “We could absolutely get better and we strive to do that,” she said.

Regarding student protests of the network’s strict discipline policy, Jones said it was premature to discuss any changes. But she said she was spending time with people “to understand how we can get better in this next chapter.”

She also briefly mentioned Noble teachers’ allegations that management has illegally interfered with unionization efforts.

“Our teachers have the right to unionize or not unionize,” Jones said. “As we stand here today they have not filed a petition.”

Noble Chief Financial Officer Alejandro Ramirez noted that the network was running a surplus. In the fiscal year that ended June 30, the network had revenue of $175 million with $10 million in surplus after expenses, compared with a $9 million surplus in fiscal year 2017.