"I love these kids," Donald Trump gushed not long ago about the young undocumented immigrants known as "Dreamers." And yet the U.S. president had a curious way of showing his affection on Tuesday, ending the program that allows 800,000 people brought to the U.S. as children to stay in the country, and forcing Congress to devise a quick fix.

In six months, the government will stop renewing protections under Deferred Action for Childhood Arrivals. The Obama-era DACA permits shielded people brought in illegally as minors from deportation.

It gave hope to the Dreamers, named after the DREAM Act (Development, Relief and Education for Alien Minors) that proposed a pathway to citizenship for younger immigrants. The DREAM Act was the unsuccessful legal proposal that preceded DACA, a stopgap policy.

Once DACA is withdrawn, though, immigration policy analysts say it doesn't appear any permanent legislative solution will replace it — at least not given such a tight deadline, a fractured Republican caucus, crammed legislative agenda and a deep intra-party divisions over immigration policy.

Trump has shifted the decision-making, and potentially the blame for killing DACA, to the legislative branch:

Congress, get ready to do your job - DACA! —@realDonaldTrump

Trump himself seemed to express little faith in a legislative solution, writing in a follow-up tweet on Tuesday night that if Congress stumbles, "I will revisit this issue." Critics said that remark undermined his argument for rescinding DACA in the first place.

"Congress has tried but failed to enact a legislative solution for DACA recipients for over a decade," noted Stephen Yale-Loehr, an immigration law professor at Cornell University. "Nothing has changed politically … except that now, Congress is under a six-month gun to try to enact something."

Dysfunction in the Republican-dominated Congress, as shown through failure to repeal the health-care law, potentially spells trouble for a resuscitated DREAM Act.

3 Republican blocs in conflict

"I don't think the Republicans can coalesce around any one policy," said immigration lawyer Leon Fresco, a former Obama administration official in the Justice Department.

Never mind bipartisanship, he said. What could prove complicated enough is uniting three Republican blocs: Republicans willing to pass a DREAM Act in exchange for added enforcement measures such as Trump's border wall, moderates willing to vote for a DREAM Act without any concessions, and ultraconservatives against granting any legal status at all.

<a href="https://twitter.com/hashtag/DACA?src=hash">#DACA</a> supporters are heading to the White House this morning <a href="https://t.co/16oCTTNLvw">pic.twitter.com/16oCTTNLvw</a> —@matt_kwong

"If those three factions can't make up their mind, there's nobody the Democrats can even negotiate with," Fresco said. "It's very concerning. [Speaker of the House] Paul Ryan understood that, which is why he asked for DACA not to be eliminated."

Far fewer Democrats are in Congress today than in 2010, when the DREAM Act collapsed in the Senate by five votes.

After that failure, President Barack Obama asserted his executive authority to introduce DACA as a temporary stopgap. Enrollees who met specific criteria — meaning they came to America before age 16, resided continuously in the U.S. since 2007 and passed criminal background checks — could acquire legal status for a renewable two-year term.

Lawmakers from both sides of the political aisle have expressed sympathy for DACA protectees, reasoning there's no sense in punishing people who broke the law through no fault of their own because they were brought to America as minors.

DACA accepted as compromise

Senior Republicans, including Ryan, Senate majority leader Mitch McConnell and senators Jeff Flake and John McCain of Arizona defended the program as an institutional compromise. Trump's Chief of Staff John Kelly also wants to preserve its principles.

"It wasn't easy to come out of the shadows...but we're here to tell Trump we're here to stay," says Dreamer Luis Aguilar <a href="https://t.co/JdnDHYILNM">pic.twitter.com/JdnDHYILNM</a> —@matt_kwong

For his part, Trump claimed Tuesday that revoking DACA caused him personal anguish, saying he has a "great heart" for those impacted by his decision. Even so, he sided with immigration hardliners in his voter base after 10 state attorneys general threatened to sue, arguing the program was unconstitutional when Obama enacted it in 2012.

While there remains a chance that Congress could pass a DREAM Act, the small window of time to devise a solution makes it all the more difficult, said Alex Nowrasteh, an immigration policy analyst at the Cato Institute, a Washington think-tank.

Packed agenda for Congress

"The odds of getting there in the next six months is pretty small," he said. "Speaker Ryan has a very complicated conference he has to keep together."

<a href="https://twitter.com/hashtag/Dreamers?src=hash">#Dreamers</a> and <a href="https://twitter.com/hashtag/DACA?src=hash">#DACA</a> supporters are in front of the White House <a href="https://t.co/feblvvTDvv">pic.twitter.com/feblvvTDvv</a> —@matt_kwong

Congress already has a packed agenda. Must-pass items this month include a new spending bill, funding for Hurricane Harvey relief and raising the debt ceiling before Republicans can take on the monumental task of tax reform. Now Trump has added a high-stakes immigration push on a tight timeline to the to-do list, which could postpone other priorities.

Most Americans like DACA, according to a new Morning Consult poll. More than three-quarters of registered voters (76 per cent) favour the policy. What's more, 69 per cent of Republicans agree that the most employed and law-abiding DACA recipients should be given a pathway to citizenship or at least legal residency.

Possible leverage for border wall

Nowrasteh suspects that a "straight DREAM Act" bill without concessions would likely pass in the House and the Senate. But he also says there's virtually zero chance Republicans would roll over on granting permanent legal status to Dreamers without attaching something they want.

For example, Republicans have indicated they will use DACA as leverage for provisions such as money for the wall, passage of Trump's proposed RAISE Act (Reforming American Immigration for a Strong Economy) to put immigration into a merits-based framework, or possibly mandate more E-Verify usage for employers to check on workers' legal authorization.

Attorney General Jeff Sessions makes a statement on the plan to end the DACA program. (Susan Walsh/Associated Press)

"You combine DACA with E-Verify or a border wall or the RAISE Act, and most Democrats will leave," he said.

(In a tweet, California Democratic House representative Eric Swalwell objected to this idea, writing: "I will not give you a pass to be a slight racist on Monday so you can be fully racist on Tuesday.")

I reject. I will not give you a pass to be a slight racist on Monday so you can be fully racist on Tuesday. <a href="https://twitter.com/hashtag/DREAMers?src=hash">#DREAMers</a> <a href="https://t.co/9fQlmLLzGs">https://t.co/9fQlmLLzGs</a> —@RepSwalwell

Nowrasteh said hardliner Republicans demanding such measures would be unlikely anyway to support what they consider to be illegal amnesty. That means for Republicans, he said, "adding these sweeteners actually makes the whole bill more bitter."

It's a "split the baby" scenario, says Republican strategist Evan Siegfried, with Democrats needing to decide what provisions they would consider in order to preserve DACA.

"When push comes to shove, will they vote for it if the RAISE Act is attached?"

An immigration battle over DACA "is clearly the big political fight of the moment," said Mae Ngai, author of Impossible Subjects: Illegal Aliens and the Making of Modern America.

"The danger is that Republicans will exact a high price for that in terms of other immigration measures."

Any DREAM Act legislation is almost guaranteed to be coupled with immigration provisions Democrats would find objectionable, but also necessary to offset "the serious ramifications that would come with amnesty," says Art Arthur, an immigration hardliner with the Center for Immigration Studies, a think-tank that lobbies for less immigration.

"A significant number of Republicans and a huge number of Democrats want DACA," he says. "The question becomes: What are they willing to accept in order to receive that?"