Years before its public implosion this week, Families for Excellent Schools stood at the center of New York’s charter-school sector and the rough-and-tumble politics surrounding it.

At its peak in 2014, the pugnacious charter-school advocacy group deployed thousands of parents and teachers to Albany to flex the sector’s political muscle and promote charter-friendly legislation. It launched a multi-million dollar ad campaign slamming New York City’s new charter-skeptical mayor, Bill de Blasio. And it helped secure a major policy victory that provided public space or rent money for the city’s new charter schools.

Now, four years later — and over a period of just a few days — Families for Excellent Schools has come crashing down.

Its demise was hastened by a series of recent blowups, including the organization’s decision last week to fire its founder and CEO, Jeremiah Kittredge, following an investigation into “inappropriate behavior.” That led its closest ally, Success Academy Charter Schools, to cut ties with the organization. And in September, the group’s political arm was forced to pay a record-breaking fine and to reveal its donors, following a disastrous political campaign in Massachusetts.

But well before its sudden collapse, the group’s influence had been waning as it became more politically isolated, observers said — in part because of its combative style and deep ties to Eva Moskowitz, Success Academy’s polarizing leader. As Moskowitz and Families for Excellent Schools kept up their relentless attacks on the de Blasio administration, other charter groups that had adopted a more diplomatic approach questioned its efficacy.

“Did it get the attention of the administration? You bet it did,” said Steven Zimmerman, co-director of the Coalition of Community Charter Schools, which brings together independent charters based in New York City. “But in the long run, what does that do?”

When it launched in 2011, the organization’s mission was less controversial: To tap the political power of charter-school families by converting them into advocates, leading get out-the-vote efforts, and coordinating political efforts among the city’s charter-school networks.

But its leaders soon found that training parents on how to organize politically and show up at local community meetings was painstaking work. At the same time, the group was growing closer to Moskowitz: At one point, some Families for Excellent Schools staff members worked out of Success Academy’s offices. Soon, it was attacking de Blasio, who had singled out Moskowitz for criticism during his campaign.

After the mayor blocked three of Moskowitz’s schools from opening or expanding, Families for Excellent Schools helped stage a 2014 rally in Albany that drew 11,000 attendees — among them many families and students from Success, which cancelled classes so they could attend. The rally, which featured fiery pro-charter remarks from Gov. Andrew Cuomo, overshadowed one that de Blasio held at the same time to promote his prekindergarten plans.

In a short span, the group had shifted from parent organizing to the flashier, more combative politics favored by Moskowitz and its pro-charter donors.

“The idea that a small group of parents met with a legislator is just not as sexy as 17,000 parents marching across a bridge,” said Sharhonda Bossier, who co-founded Families for Excellent Schools with Kittredge and now works for an unrelated education non-profit. “There was a ton of pressure from the philanthropic community to behave that way.”

In 2014, Families for Excellent Schools spent $9.6 million on lobbying — more than any other group in the state. With backing from a deep-pocketed board and donors including the Walton Foundation (which also provides funding to Chalkbeat), the group expanded into a $20 million operation by 2016. It also established a political arm outside New York, which helped pour $15 million into the pro-charter Massachusetts ballot measure.

But as it grew, the political combat it specialized in was becoming less in demand. State legislators passed laws to help charter schools expand and operate, and tensions eased between New York City’s charter sector and de Blasio.

“It has been less of an us versus them and more finding opportunity to work together,” said KIPP spokesman Steve Mancini.

Families for Excellent Schools did not join in the detente. Instead, it expanded its assault on de Blasio to include issues not directly related to charter schools. It used controversial state data to paint the city’s district schools as chaotic and violent, and denounced de Blasio’s expensive school-improvement program.

“It had really become about fighting [with] a mayoral administration that most people [in the charter sector] actually agreed with” on a range of other issues, said Bossier, the Families for Excellent Schools co-founder.

In a statement, a Families for Excellent Schools representative said the group advocated on behalf of a “a diverse coalition of public charter schools and families.”

“The accomplishments we’re most proud to be a part of — the landmark school facilities law and a series of increases in per-pupil funding for charter students — benefitted public charter schools that work closely with the de Blasio Administration and those that are more skeptical of the Mayor’s agenda,” said the statement.

Meanwhile, Families for Excellent Schools had developed ambitions outside New York. It expanded to Connecticut and Massachusetts, where it poured resources into the ballot measure in favor of charter expansion. Voters overwhelmingly rejected it.

And echoing their counterparts in New York, some Massachusetts charter groups worried that Families for Excellent Schools’ no-holds-barred tactics hurt the sector’s public image.

“The bipartisan coalition that was strongly in support of charter schools — equally Republican, equally Democrat, equally independent — has been shattered through this campaign and the tactics employed by Families for Excellent Schools,” Marc Kenen, who ran the organization that filed the state’s ballot initiative, told WBUR.

Adding to Families for Excellent Schools’ bruising defeat, the group was slapped with a $426,500 fine for failing to disclose campaign donors and was barred from election-related activity in the state for four years. The high-profile failure, as well as a settlement that forced the disclosure of its donors, created new fundraising challenges, some observers said.

Back in New York, some of the charter networks the organization once courted — such as KIPP — had been developing their own advocacy and parent-mobilizing operations since well before last fall, leaving the group with fewer allies to fall back on.

Those former clients “stopped being willing to pay for [Families for Excellent Schools’] services as parent organizer or trainer,” said one charter school observer, “which meant, also, that Success was increasingly the organization’s only major validator.”

As a result, the group was left reeling last week when Success Academy announced — after Kittredge’s public firing — that it was parting ways with Families for Excellent Schools.

“Success Academy ended its relationship with FES last week, upon learning of the investigation into Jeremiah Kittredge’s actions and his termination,” said Ann Powell, a spokeswoman for the charter network.

A few days later, Families for Excellent Schools said it planned to shut down.

Monica Disare contributed reporting.