The progressive resistance to President Donald Trump is gearing up for its next big fight — trying to protect 800,000 immigrants who could suddenly be vulnerable to deportation.

Trump is reportedly close to a decision to cripple or kill the Deferred Action for Childhood Arrivals program, which protected DREAMers — unauthorized immigrants brought to the US as children or young teenagers — from deportation. If he follows through on that threat, hundreds of thousands of immigrants who graduated from American high schools and are legally allowed to work will find their lives in jeopardy.

United We Dream, perhaps the biggest DREAMers advocacy group in the country, is prepared. New banners saying #DefendDACA arrived at the offices of the immigrant rights groups last week. The yellow vests and bullhorns arrived a few days ago. Orange brochures emblazoned with the cartoon of a girl defending young immigrants are already designed and just waiting to be printed and shipped to hundreds of members of Congress and thousands of people around the country.

“We’re ready for a national emergency call to action,” said Greisa Martinez Rosas, the advocacy director of an organization with more than 100,000 members and 55 chapters. “Any Republicans or Democrats not on our side better believe we’ll be at their offices, in their churches, and wherever they get their late-night drinks to make sure they know what’s at stake and that we wont go away until the rights of immigrants are protected and safe.”

The left-wing resistance to Trump has leaned heavily on the other two branches of government. Democrats in Congress, plus three key Republican votes, defeated the GOP health plan. The courts have narrowed and delayed, if not defeated, Trump’s travel ban. But Trump has much more unilateral control over DACA — and so protecting the immigrants who would be affected by its demise could be the toughest challenge yet.

The inside game: taking the fight to Congress directly

So far, those campaigning to save DACA have held off on taking the fight to Congress because they fear it would play into Trump’s hands.

That’s partly out of fear that doing so would give cover to the White House to say that Congress bears responsibility for protecting these undocumented immigrants. One conservative argument against DACA is that President Obama’s White House overstepped in its authority in creating the program. Immigrants activists worry they would risk appearing to agree by asking Congress to intervene.

They also aren’t willing to give up on Trump changing his mind. “We’ve been trying to push the administration to save this program, so we don’t need a legislative fix,” said Angel Padilla, a spokesperson for Indivisible, a left-wing resistance group. “That’s been the focus for now. We don’t want to give Trump the cover to say, ‘See, I don’t have the authority to keep this program in place, and it’s up to Congress.”

Of course, that calculus changes if Trump follows through on his threat to end DACA. Then the best chance at stopping him likely lies in legislation that would give DREAMers not just protection from deportation, but give them a path to citizenship.

Activists are readying an all-out push to pressure Democrats and Republicans to back S-1615, the latest Senate version of the DREAM Act, which would provide a direct path to citizenship for DACA recipients. The bill was introduced by Sen. Lindsey Graham (R-SC) and cosponsored by two other Republicans — Sens. Jeff Flake (R-AZ) and Lisa Murkowski (R-Alaska) — as well as four Senate Democrats.

Michael Vagnetti, of an Indivisible chapter in New York City, said dozens of activists would be launching a call-in campaign to get Sen. Kirsten Gillibrand (D-NY) to formally co-sponsor the legislation. (Gillibrand is an outspoken defender of DACA and immigrant DREAMers.) “We’ll be using our muscle to pressure Democrats into backing this,” Vagnetti said.

But the main push will be to get Republican lawmakers to feel enough heat that they back Graham’s bill or something close to it. Immigrant groups like United We Dream and the Church World Service have prepared scripts for DACA’s defenders to use when calling their members and urging them to save the program.

The Congressional Hispanic Caucus declined to comment for this story, citing its desire to keep its plans private for now. But one CHC aide, speaking on background, said the caucus held a conference call this week to discuss its emergency reaction strategy should DACA be rescinded. He noted that Rep. Luis Gutierrez (D-IL) was arrested at the White House in protests celebrating DACA, and speculated that similar tactics would be employed this time. Similarly, one Senate Democratic aide said that the caucus would “be doing everything we can” to emphasize that Senate Republicans, particularly Sen. Graham, supports DACA.

"We've been meeting with members of Congress to be sure they're ready to respond to this attack on immigrant young people," Martinez Rosas, of United We Dream, said. “If anyone in Congress thinks we’re going to go silently into the night and accept this, they haven’t been paying attention.”

The outside game: the resistance plans to mobilize for DACA nationally

Beyond lobbying members inside the halls of Congress, organizers are preparing a national campaign of calls, street marches, vigils, and fasts in case the DACA threat materializes.

On Tuesday morning, Abril Gallardo of Living United for Change in Arizona (LUCHA) helped bring 70 people outside the Immigration and Customs Enforcement offices in Phoenix, Arizona. She says they’ll be there all week, every day, through the night.

“It wasn’t an easy battle, but we won DACA because we got arrested and put pressure on lawmakers and that’s why we won,” she said.

Church World Service, an advocacy organization, is planning a "hunger fast" in Washington to "stand in solidarity with the DACAmented community,” as undocumented immigrants protected from deportation through the program are known. The fast is expected to begin on September 5 with a 24-hour vigil outside of the White House, and follow-up protests and civil rights disobedience actions are underway.

During the health care fight, activists sought to create enough bad publicity about the Republican bill to repeal Obamacare that members of Congress became aware of its political toxicity.

“Every senator has a mental Richter Scale in which they can measure the scale of the upheaval caused by any political movement. They look to a key set of signals for how destructive an earthquake is going to be,” Ben Wikler, legislative director of MoveOn.org, told me at the time. “The question is whether the resistance can now create not just smoke and mirrors, but the reality of a career-ending political decision for these senators so they vote against this.”

That feat will be significantly more difficult over DACA. When the Russia scandal wasn’t in the headlines, the media focused almost exclusively on health care. But now resistance leaders are trying to build a movement against DACA amid one of the worst natural disasters in American history, a new push for tax reform, fears of a government shutdown, and an impending debt ceiling crisis.

The resistance prepares for self-defense

Over the past few months, Javier Valdes and his organization Make the Road have trained families how to be ready if ICE agents arrive at their door.

“Part of it is about having a conversation ahead of time with your sister, your brother, your aunt, or your grandparent, or your neighbor: ‘Will you take on the responsibility for watching my children if I get taken away?,’” Valdes said. “It is, of course, the hardest conversation.”

Valdes is prepared to dramatically accelerate these trainings if an additional 1 million immigrants become subject to deportation in case DACA gets rescinded. “These trainings will make us go into overdrive and try to make sure as many people are trained in their rights as possible,” Valdes said. “We’re preparing families for the moment ICE knocks on your door.”

The moment Trump touches the program, immigration activists say that their very first step would be to literally congregate in public squares to shelter in numbers. “We want to make sure people have spaces to be together and feel safe — which means mass vigils and mass gatherings,” said Maria Fernanda Cabello, a volunteer organizer with Cosecha.

Trump may have the first move. But immigration activists say he won’t have the last.

“We’ll all congregate in the same office where we saw him clinch the presidency in CNN,” said Martinez Rosa, of United We Dream. “There will be some tears and some anger. And then we’ll ground ourselves by executing our plan to defend our program.”