Even though Mark Krikorian is a second-generation American, he spoke only Armenian by the time he went to kindergarten in Cleveland decades ago.

Members of his extended family had fled Turkey during a time of persecution and genocide in the early 20th century, and put special value on trying to preserve their language and ethnic heritage in their new homeland.

Yet Mr. Krikorian’s experience assimilating into a wider American culture shaped what turned out to be a lifelong mission to preserve a “shared sense” of the United States’s unique national identity, he says.

Today he’s an advocate for tighter controls on legal and illegal immigration – partly on the idea that it’s unfair if an immigrant tide makes it harder for current residents to rise rise up the socioeconomic ladder.

Ricardo Aca, a senior at Baruch College in Manhattan, has a different concern about fairness. He’s one of about 800,000 undocumented immigrants to whom the Obama administration policy granted a temporary reprieve from the threat of deportation, since they arrived in the US as children.

“We trusted the government to come forward and to come out as undocumented. They took our fingerprints. They took all our personal information. They know everything about us.”

And now, he says, they feel betrayed.

The issue of fairness animates both sides in the deeply emotional debate that’s now flaring over the status of the Obama-era Deferred Action for Childhood Arrivals (DACA) and its recipients, often called “Dreamers.” President Trump is now moving to fulfill a campaign promise to end DACA, while giving Congress six months to come up with a permanent solution to what both sides agree is a complex and even wrenching issue.

Mr. Trump’s move this week is easily one of most contentious in a young presidency already brimming with partisan rifts.

“We feel so betrayed, because we put our full trust in this country, which we’ve called our home,” says Mr. Aca, who’s studying public and international affairs. “We’ve established our lives here, we contributed just as much as any other American, even though we don’t have the same benefits.”

Illegal use of executive power?

But Republican critics insisted from the start, back in 2012, that Obama’s action was an illegal exercise of presidential power. Nine conservative state attorneys general, led by Texas Attorney General Ken Paxton, had threatened to sue the Trump administration if it didn’t end the program by Tuesday.

Earlier this year, Trump called the issue “one of the most difficult subjects I have, because you have these incredible kids.” And though he had campaigned on the promise to immediately end DACA, he said he would deal with the matter with “great heart.”

But in the end, the president’s legal team did not feel they could defend the order in court. In a press conference Tuesday, US Attorney General Jeff Sessions announced that the Department of Homeland Security “should begin an orderly, lawful wind down, including the cancellation of the memo that authorized this program.”

Mr. Sessions echoed many of the arguments espoused by Krikorian, who now heads the Center for Immigration Studies, a Washington think tank that advocates for strict immigration controls and supports most Trump policies on the issue. Sessions said the administration’s move “will further economically the lives of millions who are struggling…. And it will enable our country to more effectively teach new immigrants about our system of government and assimilate them to the cultural understandings that support it.”

Krikorian acknowledges that his own views will seem odd or even hypocritical to some.

“There’s the old value, your grandparents came here, so how can you be so critical of immigration?” says Krikorian, a fierce critic of what he calls the “lawless amnesty” decreed by President Obama, which persisted due to congressional inaction. “Well, government policy isn’t about what’s good for my grandparents, it’s what’s good for my grandchildren.”

“We need a breather,” he continues. “Lower levels of immigration are not going to fix everything, and we have a lot of problems, but it will enable our children to be able to handle and work through those problems more easily than if we continue to exacerbate them by letting in a million people every year without end.”

Why ‘Dreamer’ debate is so sensitive 

Yet in the name of fairness and compassion, both Republicans and Democrats tend to agree that Dreamers are a special case. Most did not choose to break the law coming into the country as minors with their parents, and the process of uprooting them from their established lives seems unnecessary.

“It’s not only unfair, it’s cruel. It’s psychological cruelty,” says Salvador Reza, an immigration activist in Phoenix. The government “promised them that they would be protected, they promised them that they would be able to work, and that even though they have illegal status they would be part of the society,” Reza says.

But DACA was never meant to be a permanent solution, most advocates and critics agree. In fact, since it must be renewed every two years, most Dreamers remain in status limbo.

House Speaker Paul Ryan issued a statement Tuesday saying DACA “was never a viable long-term solution to this challenge,” and emphasizing that Trump has called on Congress to act. “The president’s announcement does not revoke permits immediately, and it is important that those affected have clarity on how this interim period will be carried out,” Speaker Ryan added. “At the heart of this issue are young people who came to this country through no fault of their own, and for many of them it’s the only country they know.”

His comments hints at how sensitive the issue is for Republicans, as pressure within the party to get tough on border security runs up against the human implications of a change in course. Ryan voiced the hope for “permanent legislative solution that includes ensuring that those who have done nothing wrong can still contribute as a valued part of this great country.”

The road to a possible deal

Advocates for restrictions on immigration say Trump’s victory means that his priorities should be included in any DACA deal.

“Isn’t that the way the legislative process works?” asks Dan Stein, president of the Federation for American Immigration Reform in Washington.

Indeed, many advocates for the president’s immigration policy are willing to consider a limited amnesty for the plight of Dreamers. But if any Republican is going to consider the “amnesty” word – which is toxic to many of their constituents – Mr. Stein suggests that any deal should include legislation that pays for a border wall, more detention facilities, greater curbs on legal immigration, as well as the implementation of E-verify, an online system that allows businesses to instantly check a person’s immigration status before making a hire.

For Andrea Valdez, however, being at the center of legislative horse trading only sets her on edge.

Now in her early 20s, she was just 5 when her family came to this country from Mexico on a tourist visa and stayed. Had it not been for DACA, Ms. Valdez says, she wouldn’t have been able to get a driver’s license or a Social Security number that allowed to get work as a sales clerk. It also allowed her to get a cosmetology license that capped her two years in a high school vocational program.

It took her two years to apply for the program because she was hesitant about sharing personal information with the federal government about herself and her family, which includes both US citizens and undocumented members.

Eventually, however, it gave her peace of mind. “They gave us everything so that we could do things right,” Valdez says. “For them to just take it away from us, it makes no sense to me. It’s really unfair and it scares me because, if they do take it away, what are we going to do?”

Lourdes Medrano contributed to this article from Tucson, Ariz.