Traditionally, conservatives have maintained a monopoly on the kind of rhetoric that imagines dismantling large pieces of the federal government, calling for the abolition of everything from the Departments of Energy and Education to the Internal Revenue Service. In response, Democrats have typically dismissed these calls as the spasms of a lunatic fringe.

But President Trump’s outrageous immigration policy has led Democrats to create their own abolition movement.

“Abolish ICE”—a call to dismantle the Immigration and Customs Enforcement agency—has moved quickly from the left wing of the party to a central message for Democrats as they head into the midterms. It was everywhere at last week’s nationwide protests against family detention, and it was a prominent part of Alexandria Ocasio-Cortez’s earthshaking campaign for Congress in New York’s 14th Congressional District—a race in which she rallied the base to unseat a powerful incumbent in a Democratic stronghold.

The sudden traction of “Abolish ICE” has rattled some Democratic leaders, who fear alienating moderate and independent voters. But that fear is based in a misreading of the electorate. Ahead of an election where enthusiasm may make the crucial difference, Democrats should see this rhetoric—this energy—as a critical asset.

Leading contenders for the 2020 Democratic presidential nomination, hoping to capture some early favor with the base, are leading the charge. “I don’t think ICE today is working as intended,” said New York Sen. Kirsten Gillibrand during an interview with CNN. “I believe that it has become a deportation force, and I think you should separate the criminal justice from the immigration issue.” Sen. Elizabeth Warren of Massachusetts wrote in a Facebook post that “the President’s deeply immoral actions have made it obvious that we need to rebuild our immigration system from top to bottom, starting by replacing ICE with something that reflects our values.” And after initially declining to back calls to abolish ICE, Vermont Sen. Bernie Sanders joined the chorus on Twitter this week. “In 2002 I voted against the creation of DHS and the establishment of ICE,” he wrote. “That was the right vote. Now, it is time to do what Americans overwhelmingly want: abolish the cruel, dysfunctional immigration system we have today and pass comprehensive immigration reform.”

The roar has gotten so loud that Trump felt compelled to respond, blasting Democrats as “weak on crime” for attacking the agency. “When we have an ‘infestation’ of MS-13 GANGS in certain parts of our country, who do we send to get them out? ICE! They are tougher and smarter than these rough criminal elements that bad immigration laws allow into our country,” said the president. “Dems do not appreciate the great job they do!” Trump has said he’s “actually quite happy” to talk about ICE, and went so far as to predict that Democrats are “going to get beaten so badly” in November.

Trump’s assessment may be hyperbole, but the concern that the issue could play to his advantage has been echoed by reticent Democratic leaders and a chorus of skeptical pundits. “ICE does some functions that are very much needed,” said Sen. Minority Leader Chuck Schumer in response to calls to end the agency. “Reform ICE, yes. That’s what I think we should do.” Speaking to broader shifts among Democrats and Ocasio-Cortez’s victory in particular, Illinois Sen. Tammy Duckworth warned, “I don’t think you can go too far to the left and still win the Midwest.”

In the Washington Post, columnist Karen Tumulty wrote that “[d]emonizing a government agency is an old, tired strategy — one that rarely if ever has worked,” and cautioned Democrats that they are “heading into dangerous political territory.” The USA Today editorial board that “[w]hile Trump’s immigration policies are hugely unpopular, abolishing the Immigration and Customs Enforcement agency is not a message the mainstream will buy.”

Underlying this debate is a specific theory of the electorate as a battleground for persuadable independents. USA Today cites some numbers: “In the 2016 election, for instance, 35% of voters identified themselves as conservative while only 26% said they were liberal. The largest group — 39% — called themselves moderates. Forming a liberal-moderate alliance is a necessity for Democrats.” In this view, elections are determined by that broad middle of independent, often moderate voters. Those voters swing between the two parties, with views that don’t fully align with one or the other. They’re drawn to compromise and alienated by stridency. In the case of immigration, goes the argument, they want enforcement even as they oppose the president’s harsh policies.

Trump’s assessment may be hyperbole, but the concern that the issue could play to his advantage has been echoed by reticent Democratic leaders and a chorus of skeptical pundits.

The caution shown by Democratic leaders makes sense if there is a large cohort of moderate swing voters. But there isn’t.

The story of the American electorate since the 1970s is one of ideological polarization and growing partisanship. Voters are more likely than ever to back a “straight ticket.” States that go Republican in a presidential year, for example, tend to go Republican in midterm elections and Republican in state legislatures and governor’s mansions. Critically, notes Emory University political scientist Alan Abramowitz in a new book, The Great Alignment: Race, Party Transformation, and the Rise of Donald Trump, this is true even as fewer Americans identify themselves as either Democrats or Republicans: “[W]hen pressed about their party preference, most of these ‘independents’ make it clear that they usually lean toward one of the two major parties. … When we shift our focus from partisan identification to partisan behavior, we find that leaning independents as well as strong and weak party identifiers are voting more along party lines than at any time in the past half century.”

Driving this are deep divisions within the electorate, from the “growing racial and ethnic diversity of American society” and “growing secularism and the decline of traditional religion” to the “growing influence of partisan media.” In turn, these divisions produce “negative partisanship” as “supporters of each party have come to perceive a widening gap between their policy preferences and the policies advocated by the opposing party.” Racial division, among whites in particular, is especially crucial. Beginning in the years of Ronald Reagan and George H.W. Bush, the most racially resentful whites became Republicans; the least racially resentful whites, Democrats.

Polarization and partisanship act on each other. As voters have sorted themselves across the ideological divide, they have moved away from the center. The person who votes consistently Democratic may reject the party label, but over time, their views begin to align with that of other Democrats. They become more consistently liberal. On the other side, regular Republican voters become more consistently conservative. This is one reason the share of “purple” states has fallen, as conservative electorates become solidly Republican while liberal electorates become solidly Democratic.

There are some “pure independents” and genuinely moderate voters. But they compromise a small and unrepresentative share of the electorate. They are less likely to pay attention to political debates and less likely to vote. Most voters who call themselves “moderate,” notes Abramowitz in an earlier work, “have a clear ideological orientation” and consistently partisan voting behavior.

Critics of “Abolish ICE” are right that it will alienate moderate and independent voters. But most likely, those who are put off by the policy will be those “moderates” and “independents” who already vote for Republicans, and who already oppose immigration. After all, the electorate has already been severely polarized by Donald Trump, who began alienating broad swaths of the electorate in 2015 with his racist, anti-immigrant rhetoric. But those voters were either Democrats, or trending against Republicans before Trump. For their part, GOP voters stuck with their nominee and those voters trending Republican (whites without college degrees) continued on their path. That retrenchment runs deep. In December, GOP voters in Alabama stuck with Roy Moore despite credible accusations of sexual assault, allowing for a victory by Doug Jones, a Democrat who didn’t so much convert Republican voters as he mobilized Democrats and capitalized on a weary opposition.

Modern elections don’t turn on capturing a mythical “center,” they turn on activating, expanding, and mobilizing your base and demoralizing the opposition. Recent swings in election outcomes—from 2008 to 2010, or 2012 to 2014—reflect changes in the composition of the electorate. “The data suggests that the rise and fall of the incumbent party’s fortunes may not be driven by the movement of independent voters from one party to the other, but instead, by the entrance (and exit) of partisan voters who are activated or deactivated by negative partisanship,“ explains Rachel Bitecofer, assistant director of the Wason Center for Public Policy at Christopher Newport University, in a “state of play” for the upcoming midterm elections.

The political measure of “Abolish ICE” and other forms of liberal outrage isn’t whether it will alienate moderates or independents, or whether Trump hopes to speak about the issue. And fear that it will help Trump mobilize his voters is unwarranted: Virginia Republicans tried to run against “MS-13” and “illegal aliens” to no avail, suffering deep losses in districts where Trump won majorities. The political measure of this rhetoric is whether energizes Democratic voters—whether it differentiates the party, speaks to genuine feelings among voters, and provides a focal point for campaigns and activists. Looking at those Democrats who have adopted the call—who see political advantage in taking a stand against the agency—the answer to all those questions is yes. As the party begins to align against ICE and its aggressive immigration enforcement, expect large parts of the public to move along too, as people who vote for Democrats adopt Democratic positions.

The message’s already-swift movement into the mainstream illustrates how the field of possible opinion in American politics is wide open in a way we haven’t seen since the 1960s, or even earlier. Demographic change—from racial and ethnic diversity to new, younger cohorts of voters—is working its way through our elections, and, after a generation of loose consensus around markets and deregulation, a resurgent left is pushing social democracy. “Abolish ICE” may not be a slogan for the present, yet, but there’s no question it’s a symbol of the party’s future.