In a bold declaration of independence from status-quo politics, the New York Working Families Party on Saturday endorsed Cynthia Nixon’s progressive challenge to Governor Andrew Cuomo.

The WFP, which was founded two decades ago as a unique political grouping that applies inside-outside pressure on the Democratic Party, has its own ballot line in New York. It usually gives that line to Democrats. In 2010 and 2014, for instance, it backed Cuomo, despite the fact that his policies were more centrist than those favored by many WFP activists.

This year, however, the WFP has abandoned Cuomo in favor of Nixon, the actress and education activist who is mounting a fiercely progressive Democratic primary challenge to a governor she says is too corporate and too compromised. Nixon accepted the endorsement in the language and the spirit of her grassroots campaign, announcing that “With the [New York Working Families Party] by our side, we will fight for equitable schools, good jobs, single-payer health care, subways that actually work, environmental justice, and an end to mass incarceration. It’s time for a New York that belongs to all of us—for the many, not the few.”

Support for Nixon was so overwhelming that Cuomo chose not to compete for the WFP endorsement, for which Nixon secured 91.5 percent of the vote at Saturday’s state committee meeting in Albany.

Despite the fact that he did not formally seek the WFP endorsement, Cuomo tried to manipulate the process—by pressuring major unions that have long been associated with the party to exit its fold. Two unions, Communications Workers of America District 1 and Service Employees International Union Local 32BJ, quit the WFP on the eve of the endorsement vote.

But frustration with the Cuomo administration’s corporate ties and compromises on a host of public-education, housing, rural poverty and criminal-justice issues was so great that the WFP endorsed not only Nixon’s run against the governor but also the progressive challenge being mounted by New York City Councilman Jumaane Williams to Democratic Lieutenant Governor Kathy Hochul.

The WFP’s decision strengthens Nixon’s hand in what remains an uphill primary run against Cuomo. Were she to win the Democratic nod, she could bid in November on both the Democratic and WFP lines—as New York allows parties to “cross endorse” candidates and merge the votes in the general election.

That means that the WFP endorsement has major implications for New York politics in 2018. But it is also a big deal nationally. Nixon is one of many insurgent candidates challenging centrist and corporate-tied Democrats this year, with messages that frequently parallel those framed by Vermont Senator Bernie Sanders in his 2016 presidential run.

Appearing in Washington earlier in the week, at a gathering of progressive candidates organized by the Progressive Change Campaign Committee, Nixon grouped herself with the left-leaning contenders “the Democratic establishment didn’t want…to run.” Noting Cuomo’s campaign bankroll, and those of other corporate-tied Democrats, Nixon observed: “It’s hard for some Democrats to do right when they’re getting millions and millions to do wrong.”

“The time is up for corporate Democrats, for politicians who campaign as Democrats but govern as Republicans,” Nixon told the crowd. “If we’re going to get at the root problem of inequity, we have to turn the system upside down. It’s not just about getting more Democrats in office but about getting better democrats—ones accountable to voters, not corporate donors.”

Nixon drew cheers as she declared: “If we want change, we have to do what we’ve always done—we have to go out ourselves and we have to seize it.”

On Saturday, she seized a coveted endorsement for a high-profile governorship—and in so doing sent a signal that the fight for the future of the Democratic Party, and the country, is on.

“Let’s get out there. Let’s knock on some doors,” Nixon told the WFP gathering in Albany on Saturday. “Let’s organize. And let’s win this thing!”