Hundreds of women protested against family separation and detention on Thursday in Washington, DC. They were also calling for the abolishment of ICE.

Calls to “abolish ICE” have been building in recent weeks, as the Trump administration’s “zero tolerance” border policies have pushed the platform into the mainstream among some Democrats.

ICE is shorthand for US Immigration Customs and Enforcement, and many activists on the left see the agency as emboldened and out-of-control under Trump. (It’s also separate from US Customs and Border Protection, which acts as the border patrol; ICE acts as an interior patrol.)

Just this week Rep. Mark Pocan (D-WI) announced he was introducing a House bill to dismantle ICE in favor of a more “humane” border enforcement. In New York, Alexandria Ocasio-Cortez — who upset Rep. Joe Crowley (D-NY) in the 14th District’s congressional primary — has called for the abolishment of ICE, and she’ll almost certainly be elected to Congress in the fall.

But not all Democrats are ready to join the call. CNN’s Jake Tapper asked Bernie Sanders (I-VT) this week about abolishing ICE. The senator refused to answer the question, saying we need to “create policies that deal with immigration in a rational way” — and swiftly got blowback from his supporters.

“Abolish ICE” has also become a potent rallying cry in demonstrations against President Donald Trump’s family separation policies that have popped up across the country. Protesters confronted Department of Homeland Security Secretary Kirstjen Nielsen with such chants as she dined at a Mexican restaurant last week.

Similarly, protesters who gathered for the march on Thursday chanted the slogan, en masse, outside of the Justice Department.

#WomenDisobey: Chanting ABOLISH ICE at the DOJ building, a demand I’m hearing more and more - cc: @SeanMcElwee pic.twitter.com/T6U9nRw6EM — Alejandro Alvarez (@aletweetsnews) June 28, 2018

What to know about the “Abolish ICE” rallying cry

“Abolish ICE” began as pushback to aggressive immigration enforcement. Trump’s hardline agenda was a driving force behind the movement, but immigration activists and others largely see ICE as a problematic part of the larger immigration enforcement apparatus, as Vox’s Dara Lind wrote in her detailed explainer.

ICE came into existence in the early 2000s, when the federal government was reorganized and the Department of Homeland Security was created — so it’s a relatively new branch of the federal government. Its creation led to more deportations, which escalated during the Obama administration, especially during his first term. But it is under Trump that worries about the agency’s overreach grew.

Leftist activists are vilifying ICE as a symbol of all that’s wrong with US immigration policy — especially because any viable legislation solution is basically dead on arrival in Congress. It’s also a challenge to Democrats as the progressive and more mainstream wings of the party battle it out.

A push to abolish ICE wouldn’t be the end of immigration or border enforcement. Pocan, who is introducing “Abolish ICE” legislation, said he’s looking to transfer necessary functions to other agencies. Even Ocasio-Cortez isn’t calling for open borders, but instead emphasizing a renewed focus on security rather than just enforcement.

“In a similar way where we have law enforcement enforce legitimate crimes of violence, crimes of harm, mass, large fraud,” Ocasio-Cortez told Documented NY. “I think that there is a role for enforcement there, but I do not think that it in any way is equivocal to what we are seeing with ICE right now.”

This, in many ways, is the activists’ strategy working. A radical idea — abolishing ICE — transformed into a more viable, and potentially achievable, political plan.

Correction: This post misstated Pocan’s party. He is a Democrat.