WASHINGTON — "Abolish ICE!" It's become a fast-growing slogan among progressives rallying against deportation and a favorite new foil for Republicans aligned with President Donald Trump's immigration agenda.

Immigration activists have long protested Immigration and Customs Enforcement (ICE), which enforces immigration law away from the border, arguing the agency lacks oversight and that its mission breaks up families by targeting otherwise law-abiding migrants.

Those complaints have spread under Trump through broader liberal circles, with a growing number of candidates and elected officials adopting "Abolish ICE" positions. They include House candidate Alexandria Ocasio-Cortez, who visited the border to draw attention to the message shortly before she upset Democratic Rep. Joe Crowley in Tuesday's primary election.

Sen. Kirsten Gillibrand, D-N.Y., came out for replacing ICE with a new agency Thursday, saying it had become a "deportation force." "We should abolish ICE," New York City Mayor Bill de Blasio said Friday on WNYC.

The Democrats are making a strong push to abolish ICE, one of the smartest, toughest and most spirited law enforcement groups of men and women that I have ever seen. I have watched ICE liberate towns from the grasp of MS-13 & clean out the toughest of situations. They are great! — Donald J. Trump (@realDonaldTrump) June 30, 2018

For the moment, "abolish ICE" is still largely a rallying cry without a policy behind it. It could mean anything from spreading ICE's functions across government to ending its mission entirely, depending on who you ask.

That's changing fast. Rep. Mark Pocan, D-Wisc., announced this week he would put out a bill to "abolish ICE and crack down on the agency's blanket directive to target and round up individuals and families." Other Democrats, including Ocasio-Cortez if she wins in November, are planning to pursue legislation, as well.

Pocan, who co-chairs the House Progressive Caucus, recently sat down with NBC News to discuss his vision for the movement, the Republican backlash, and the role of immigration enforcement in a post-ICE world. The conversation is below, edited for length and clarity.

NBC NEWS: "Abolish ICE" has emerged as a rallying cry over the last few months, but when I talk to activists they sound unsure how to define exactly what it means. How do you put policy to this idea?

Pocan: Rather than put a prescriptive 'This is exactly what you have to do' — because there can be lots of opinions how to best get it done — we're recommending a commission lay out the duties that need to continue that ICE does that are appropriate and proper and then take away the ones that the president has maybe abused that maybe no longer need to exist.

Prior to its creation, about 20 different departments did these functions. It's not like ICE is the only entity that goes after human trafficking or gangs or drugs. You have the Department of Justice, the FBI, the Department of Labor. There are certainly ways to put those duties back to the other agencies.

So would this commission have the power to make these changes themselves? Or just send a recommendation to Congress?

We don't have the final language, but it's supposed to come back to Congress.

We have Customs and Border Protection now, which handles the border, and ICE, which handles interior enforcement. In your eyes, is there a role for an agency that seeks out people to deport?

The whole idea is that it was created after 9/11 with the terrorist actions that affected this country in mind. If you take them away from that focus because they're busy finding that person who got a speeding ticket in Kansas at a meatpacking facility, you’re not going after someone who could be a threat to a large number of Americans.

We're saying, let's get back to what the focus is, let’s go after the people who are a threat to this country in a different way than what we’re doing right now. You need to work within communities to get intelligence. ICE has such a bad reputation, and if you’re afraid you’re going to be deported no one is going to talk to them. They're not able to get the things done that we need them to get done.

It sounds like you're describing a branding problem almost as much as a policy problem.

A part of your policy is the brand. If you can't get information by working with certain communities because they think you may be deporting them, you’re not getting information that could help you go after someone who really is a threat to this country — and we all want to go after that threat. The way it’s been used by this president has unfortunately made them ineffective.

ICE was extremely controversial under President Obama as well. Can ICE be reformed without being dismantled?

If ICE on a jacket right now is what no longer allows you to get information you need because people are afraid of what that means, because of how it's been misused specifically in the last year and a half, then you have to dismantle that part of what ICE is. You don’t have to dismantle all of the functions of ICE, because some are necessary.

I checked on this issue a couple of months ago and there were very few candidates embracing it in their platform. How did this come across your radar and convince you to work on a bill?

President Trump has been an evolution for many of us in how far he will go and, I would argue, his actions that damage the country, and at what points you have to stop them.

So I think when it comes to ICE, as we talked to people in ICE detention facilities who had children separated from them in another state, and one woman was told her child would be put up for adoption, and another women they said we’ll release you and then eventually we’ll release your nine-year old daughter who is being held in New York — these are inhumane, cruel un-American things to do.

Then when the president said this weekend we can get rid of due process — he’s already abusing ICE’s functions as a personal political police force for his own reasons, and then when you add getting rid of due process, this is not what America’s about. That was really the catalyst. We started talking a little more the week after my border visit, but that was the absolute ‘no more sitting down’ moment.

Republicans are celebrating the rise of the "abolish ICE" movement, which they say shows Democrats are not committed to stopping illegal immigration or are “open borders.” How do you respond?

Obviously, they’re lying. ICE doesn’t work at the border, period, end of sentence, end of fact, end of truth. So they’re going to try to use this to manipulate the people who are either afraid of people who don’t look like them or who are outright racist. What Donald Trump has done since he’s been president is manipulate those kind of people.

So let them go ahead and do that, we’re going to put out the facts. But I think like we saw with separation of families and children at the border, he tried to manipulate that issue and it completely blew up in his face because the American people’s values are significantly more moral than our president’s. I’m willing to put those facts out there and have the debate.

That debate was supercharged Tuesday night when Alexandria Ocasio-Cortez, who emphasized abolishing ICE very prominently, defeated Joe Crowley. What do you make of her campaign?

I think we're seeing in not just that campaign, but other campaigns, that the base cares about progressive values.

Our argument to leadership now is this is a moment where this is what people want. When you ask them, 'Do you want bold change or incremental change?,' even Republicans want bold change, across all spectrums. I think sometimes the political class likes to remain safe because it keeps them in office and every now and then something happens like last night that reminds us we need to really listen to the people who are actually across the country, who are the voters.

Based on Tuesday’s results, do you think Democrats who have been in Congress a long time should be nervous about this moment where people are adopting new issues like this they weren’t prepared for? What would your advice be?

Embrace it. 'If the people lead, eventually the leaders will follow,' is a bumper sticker that I have on my car. It's true, right?