Attorney General Jeff Sessions announced on Sept. 5 that the Trump administration is rescinding Deferred Action for Childhood Arrivals, calling the program "an open-ended circumvention of immigration laws." (The Washington Post)

The Trump administration on Tuesday ordered a winding down of the Obama-era Deferred Action for Childhood Arrivals (DACA) program, which protects from deportation young undocumented immigrants who were brought to the United States by their parents. Providing no legislative road map, Trump called on Congress to “legalize” DACA before he phases out the program next March. Trump’s move puts at risk of deportation some 800,000 “dreamers” who received temporary work permits and other benefits through DACA.

It’s certainly possible that a Republican Congress — leaning heavily on Democratic votes — could pass a narrow measure to put the DACA program on firmer legal ground. But Trump’s challenge to Congress could also deepen a GOP cleavage over immigration reform, derailing action. Here’s a look at the three main barriers to swift congressional action.

People march in support of DACA from the White House on Sept. 5, 2017, in Washington. (Matt McClain/The Washington Post)

1. Polarized parties

Some Republican lawmakers, including Sens. Lindsey O. Graham, John McCain and Jeff Flake, said this week that they wanted to protect DACA beneficiaries. But more often, legislators’ positions on immigration reform diverge on party lines. It is no wonder that 1986 — some 30 years ago — was the last time the United States passed a major reform of immigration laws, in a bipartisan deal struck by a Democratic House and a Republican Senate and White House.

Since then, any such efforts have been blocked by growing partisanship and ideological sorting of conservatives and liberals into the Republican and Democratic parties. A Democratic Senate in 2013 did cobble together a bipartisan immigration deal by combining three elements: the increases in border security that conservatives wanted; the provisions for temporary agricultural workers that businesses wanted; and the path to citizenship for undocumented individuals that liberals wanted. But that bipartisan deal died when the House GOP leadership refused to bring the bill to the floor.

Democrats decried the Trump administration's decision to wind down Deferred Action for Childhood Arrivals, while many Republicans agreed that DACA was an "overreach." (Jenny Starrs/The Washington Post)

Why is Congress so divided by party on immigration? It is because members’ constituents are just as divided along party lines. What is more, Republican and Democratic congressional districts have starkly different concentrations of Hispanic voters.

As you can see below in the figure based on census data, only a handful of House districts represented by Republicans include large communities of Hispanic or Latino voters. (The 2010 Census uses the terms “Hispanic” and “Hispanic or Latino” interchangeably.) Look at the districts where Latinos make up more than 20 percent of voting-age residents and you’ll see that they more often elect Democrats than Republicans. Only about 10 percent of GOP-held districts have that many Latinos, while about a third of Democratic-held districts do.

That means that only a handful of GOP lawmakers have constituents pressuring them heavily for comprehensive immigration reform. You won’t be surprised, then, that these are the dozen or so members who have signed onto bills to legalize DACA. Nor should it be surprising that the rest of congressional Republicans have few incentives to advance comprehensive immigration reform — despite general public support for protecting DACA beneficiaries.

2. A schism among Republicans

Immigration has been missing from the GOP legislative agenda for good reason: The GOP is fractured over reform.

Business-friendly Republicans tend to favor comprehensive reform, arguing — as many businesses do — that creating clear and stable systems that allow the entry of needed workers will bring economic benefits to all. Social conservatives tend to oppose any proposals that they deem “amnesty” — forgiving individuals who are in the United States without papers and giving them a way to stay. You could see those divisions in 2013, after John McCain and several other prominent Republican senators worked in a bipartisan “Gang of Eight” to craft an immigration bill — which in the end got the votes of only 11 Republicans on the Senate floor.

Today, a handful of Republicans — including some Senate conservatives such as James Lankford of Oklahoma and Tom Cotton of Arkansas — say they favor legalizing DACA somehow. But it is not clear whether that kernel of GOP support can grow — or whether the GOP’s top leaders in Congress, Senate Majority Leader Mitch McConnell (Ky.) and House Speaker Paul D. Ryan (Wis.) have the stomach to push their respective conferences to take up immigration despite extreme party cleavages.

Nor is the White House likely to offer any political cover for Republicans seeking a path forward. Judging from the president’s recent behavior, he is more likely to lash out against inaction than lead the GOP forward.

3. Time is short, for better or for worse

The congressional calendar is very, very tight — and may leave no room for action on DACA. With a three-month agreement reached Wednesday to raise the debt limit, fund the government and provide emergency hurricane aid, lawmakers will need to reach longer-term solutions on these issues by mid-December.

Lawmakers also need to craft a bipartisan budget deal if they want to avoid automatic spending cuts in 2018 dictated by the 2011 Budget Control Act. And a bipartisan group of senators hopes to shore up the Affordable Care Act. Republicans are also desperate to reform the tax code. And if they want to avoid dealing in the Democrats, budget rules require that they first adopt a budget.

Wednesday’s agreement prolongs these battles into fall and winter — inching closer to the 2018 electoral season, when Congress often finds it even more difficult to tackle controversial issues.

Where on this crowded agenda would Congress find time for major immigration reform? Ah, but there’s a back door. Many of these measures will be must-pass, lest the government shut down or default on its financial obligations. And almost all will require Democratic votes if and when the Freedom Caucus conservatives balk, as they have in the past. That gives lawmakers a variety of targets for an amendment that would legalize DACA.

Will that happen? We don’t yet know. We’re only beginning to get a glimpse of Democrats’ strategy. Their fall wish list is long: In addition to legalizing DACA, Democrats are eager to cement insurance subsidies to strengthen Obamacare exchanges, secure more funding for domestic discretionary funding, and block Trump proposals they deem odious, such as building a wall along the border with Mexico. It is not clear yet whether Democrats will have sufficient leverage to secure all of their objectives, nor do we know how Trump would react if Congress fails to match DACA protections with more aggressive border control.

Still, there is strong public pressure to act on behalf of the highly sympathetic “dreamers,” which Democrats could leverage procedurally in the coming months. And if Republicans don’t act, Democrats go into the 2018 elections with an issue that mobilizes midterm Democratic voters, a valuable consolation prize.