When Representative Alexandria Ocasio-Cortez joined members of the Sunrise Movement and the Justice Democrats at a sit-in at Nancy Pelosi’s office pushing a Green New Deal in November, she framed the proposal, which few had then heard of, as the only way for the Party and the country to seriously address climate change. “We do not have a choice,” she told them. “We have to get to one hundred per cent renewable energy in ten years. There is no other option.”

Now, less than three months later, sixty house Democrats and nine Senate Democrats, including five announced or expected Presidential contenders—Kamala Harris, Elizabeth Warren, Cory Booker, Kirsten Gillibrand, and Bernie Sanders—have backed a resolution outlining the principles and goals of a Green New Deal. Once drafted, the legislation will be the most ambitious climate effort that Congress has ever considered. On Thursday, Ocasio-Cortez and Senator Ed Markey, the resolution’s lead sponsors, marked its introduction with a press conference outside the Senate.

“Five decades ago, President Kennedy announced the ambitious goal of sending an American safely to the moon,” Markey said. “He didn’t say how it would be done but that we would do it. We would need a giant rocket made of new metal alloys that had not been invented yet, and it would have to be returned safely to Earth within ten years. He urged us to be bold. I say today that it is time for us to be bold once again.”

“This is a big day for activists all over the country and for frontline communities all over the country,” Ocasio-Cortez said during her turn at the podium. “Today is a big day for people who have been left behind. Today is a big day for workers in Appalachia. Today is a big day for children that have been breathing dirty air in the South Bronx.”

The resolution puts forward the broad goals talked up by Ocasio-Cortez, Markey, and others but avoids some of the fault lines that have emerged between climate activists and moderate Democrats over the past few weeks. Most notably, the resolution does not explicitly call for a ban on fossil fuels, one of the ideas initially put forward by some climate activists. It instead says that the Green New Deal will work toward “meeting 100 percent of the power demand in the United States through clean, renewable, and zero-emission energy sources”—language that leaves open the possibility of sustaining or expanding nuclear energy, which had been rejected in an open letter last month from over six hundred environmental groups, including the Sunrise Movement. The resolution also does not rule out the possibility of a carbon tax—an idea favored by centrists but viewed as inadequate by many climate activists.

At the press conference, Ocasio-Cortez referred obliquely to debates over particular provisions. “When people say, what about this or what about that, the answer isn’t, ‘This is why it isn’t in here,’ the answer is, ‘That is part of the solution, too,’ and so I hope you all see that.”

For Greg Carlock, of the progressive group Data for Progress, which has offered its own Green New Deal outline and has been privy to the talks over the resolution, those debates are secondary to the task of getting members of Congress to take the Green New Deal’s overarching goals seriously. “I think some people will look at this and then tell you all the reasons why, as a legislative agenda, it’s too ambitious or controversial,” he says. “They’ll kind of say, ‘Look at the fossil-fuel ban,’ or look at renewable versus clean and all that kind of stuff. And I see this as a commitment to an effort to meet the scale and urgency of the challenges and define a vision for where we want to drive the country and society. It’s kind of asking Congress to go down on the record.”

On the specific matter of banning fossil fuels, Julian NoiseCat, of the climate group 350.org, says that the language in the resolution meshes with the goal of eliminating fossil fuels without alienating the various progressive stakeholders whom Green New Deal advocates will have to win over. “Any Green New Deal would entail conversation and compromise between the many, many actors across progressive space,” he says, “which would include labor unions that represent fossil-fuel workers—all sorts of different sectors of society. That being said, I think that, given how inclusive they’ve aimed to be in the drafting of this, there was actually some very ambitious language in there about how we are going to transition off of fossil fuel.”

The Green New Deal has always been far more than a climate plan. There are planks on strengthening antitrust policy, protecting the right of workers to organize, and providing every American with “high-quality health care” and “affordable, safe, and adequate housing.” Perhaps most ambitiously, the resolution calls for a green federal job guarantee—every American, it suggests, will have a job opportunity tied to the project of transitioning America to clean and sustainable energy. All will be paid for primarily, an F.A.Q. offered by Ocasio-Cortez’s team implies, with debt spending.

The fact that five of the Party’s leading Presidential contenders and sixty Congressional Democrats have signed onto legislation containing these proposals is remarkable. It is an even clearer sign than growing Democratic support for single-payer health care that the era of Clintonian triangulation is over—that the question leading Democrats are asking is not whether the Party should move left but how far left it should go.

The resolution is also in keeping with the Democratic Party’s longstanding strategy on climate—the Party has long assumed, probably correctly, that major climate action is unlikely unless addressing the crisis is woven securely into the Party’s economic agenda. A job guarantee, as radical as it seems, is an extension of the same logic that led the Obama Administration to tout the creation of green jobs. The resolution also ties climate action to the advancement of a variety of demographic groups, including many clearly important to the Party’s political future. There is much in the text about “frontline and vulnerable communities,” defined as “indigenous peoples, communities of color, migrant communities, deindustrialized communities, depopulated rural communities, the poor, low-income workers, women, the elderly, the unhoused, people with disabilities, and youth,” for whom the Green New Deal will also “promote justice and equity by stopping current, preventing future, and repairing historic oppression.”

As the resolution begins moving through both chambers, Representative Ocasio-Cortez, Senator Markey, and other supporters will be drafting the legislation that the Green New Deal outlines. A source close to Senator Bernie Sanders told me on Thursday that he will unveil a Green New Deal bill within the next several months. “Obviously the Green New Deal is an expansive policy,” Stephen O’Hanlon, a spokesperson for the Sunrise Movement, says. “It’s going to need to be multiple bills and long bills, so they’re working on that.” Of course, no bill they propose will be taken up unless Democrats win the White House in 2020, unseating a President who has claimed repeatedly that climate change is a hoax. In 2010, Democrats, who held the Presidency, the House, and the Senate, elected not to advance an ambitious cap-and-trade bill co-authored by Senator Markey, because they failed to secure the sixty Senate votes necessary to break a Republican filibuster. But the majority Party in the Senate can eliminate the filibuster unilaterally, provided it has fifty-one votes for doing so—a tactic used in recent years to eliminate the filibuster for executive and judicial nominees. At Thursday’s conference, I asked Markey whether, the next time Democrats hold Congress and the Presidency, they should eliminate the Senate filibuster to pass the Green New Deal. “That would be a good problem to have!” he said. “My own feeling is that this is going to be such a powerful issue in the 2020 election cycle that we’re going to have the Republican support, all across the country, to pass it with sixty votes and a supermajority in the House as well.”

The Trump-era Republican Party, though, will not be budging from climate skepticism any time soon. And, even if Democrats do extraordinarily well in the 2020 Senate elections, it is extremely unlikely that they will win sixty seats. In the best-case scenario for Democrats, the only paths forward for climate legislation are the elimination of the filibuster or, perhaps, the passage of certain tax and spending provisions through budget reconciliation, a maneuver that only requires a simple majority. These are also the only ways to pass other ambitious parts of the Democratic agenda, such as Medicare for All, now nominally supported by all of the Party’s top-tier 2020 Presidential candidates. Denial about this is widespread—no candidate, not even Bernie Sanders, has openly supported eliminating the filibuster. Deploying it would radically transform federal lawmaking and bring American politics to a new, precarious place. It is difficult to imagine Democrats building the will to consider that move easily. It was also difficult to imagine, mere months ago, that the Green New Deal would become the Party’s flagship proposal for climate action. Yet, here we are.