WASHINGTON — A bare majority of the U.S. Supreme Court appeared likely Tuesday to let the Trump administration follow through on its plan to shut down DACA, the federal program that has allowed nearly 800,000 young people, known as "dreamers," to avoid deportation and remain in the U.S.

With hundreds of DACA supporters rallying outside — so many that police shut down the street in front of the Supreme Court — the justices heard nearly an hour and a half of oral arguments. Based on their questions, it appeared that the court's five conservatives were inclined to rule that the Department of Homeland Security acted properly when it ordered the program ended in 2017 and that the federal courts cannot second-guess that decision.

While Justices Clarence Thomas, Samuel Alito, Neil Gorsuch and Brett Kavanaugh appeared likely to say DACA was properly shut down, Chief Justice John Roberts did not seem to be as strongly convinced. Roberts may be the deciding vote, just as he was last term when the court blocked the Trump administration from adding a citizenship question to the 2020 census form. He concluded in that case that the government had not given an adequate explanation for its proposed action.

Lower court rulings have kept DACA going, allowing young people in the program to reapply every two years to remain under its protection. Children of undocumented immigrants can remain here if they were under 16 when their parents brought them to the U.S. and if they arrived by 2007.

Arguing for DACA's defenders, lawyer Ted Olson said federal law requires the government to give a detailed explanation before taking an action that affects hundreds of thousands of people and the businesses that employ them.

Lawyer Theodore Olson argues for DACA's defenders before justices of the Supreme Court. Art Lien

It would be one thing, he said, "if they provided a rational explanation and took responsibility for their decision." But instead, the Justice Department has simply said the program was illegal and therefore must be shut down.

"We don't know what the administration would do if it had to own its decision and take responsibility for throwing these young people out of work," Olson said.

The court's four liberal justices seemed to agree. When the government tried to end it, "they said it was illegal and said nothing about the policy," Justice Ruth Bader Ginsburg said.

Justice Sonia Sotomayor said much more explanation was needed to justify the decision. "This is about a choice to destroy lives," she said.

But the court's conservatives suggested that the Trump administration's decision to stop enforcing DACA is beyond the power of courts to review, as would be the case if a local prosecutor decided to stop enforcing laws against possessing small amounts of marijuana.

When Olson suggested ending DACA is different, because so many people are affected, Gorsuch said, "I can think of a large number of people who would be affected by a prosecutor's exercise of discretion."

Among those nervously watching is Claudia Quiñonez of Maryland, brought to the U.S. at age 11 by her mother, who overstayed a tourist visa.

"DACA truly changed my life," she told NBC News. "I have a Social Security number. I have the ability to work, to contribute, and pay taxes."

Figures show that over 90 percent of DACA participants have a job. Nearly half are in school. Many don't speak the language or know the culture of their home countries.

The case has attracted the interest of more than 100 businesses and trade groups, including the U.S. Chamber of Commerce, which have urged the Supreme Court to allow DADA to continue. Microsoft is one of the DACA defenders whose lawsuits led to court orders that kept the program going.

The company says more than 60 DACA recipients are among its employees. "These young people contribute to our company and serve our customers. They help create our products, secure our services and manage our finances."

Apple CEO Tim Cook filed a separate friend of court brief in aid of DACA participants. "They, and immigrants like them, are vital to Apple's success. They spark creativity and help drive innovation. They are among our most driven and selfless colleagues."

A ruling in such a contentious case isn't likely until the spring of 2020, assuring that DACA will figure in the presidential campaign.