President Donald Trump's decision to end the popular Obama-era immigration program that shields young migrants from deportation will be on the line Tuesday during oral arguments in a blockbuster case at the Supreme Court.

The justices will hear extended arguments concerning whether the administration's attempted termination of the Deferred Action for Childhood Arrivals program was lawful. The program, put in place seven years ago, protects about 700,000 immigrants and allows them to receive work permits.

Trump sought to end the program in 2017 but was blocked from doing so by lower courts in California, New York and Washington, D.C. Trump has argued that President Barack Obama lacked the legal authority to institute the program, but has shied away from criticizing DACA as bad policy.

More than 4 in 5 Americans support granting U.S. citizenship to DACA recipients, who are sometimes called "Dreamers," according to a Gallup survey taken last year. More than 100 businesses, including some of the nation's largest and best known, have urged the high court to protect the program.

Read more: How Obama's border enforcer Janet Napolitano is fighting Trump on immigration at the Supreme Court

A decision is expected by the end of June, in the midst of the 2020 presidential election.

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The case is one of the most important disputes of a jam-packed term, affecting millions of Americans with ties to DACA recipients. It is also the latest test of how a conservative Supreme Court with two Trump appointees will treat the president's policies.

The court has shown some deference to the president's immigration agenda — it allowed him to use disputed funds for construction of the U.S.-Mexico border wall and approved a version of his travel ban — but has also at times ruled against him. Justice Brett Kavanaugh replaced Justice Anthony Kennedy after the court's travel ban ruling.

In June, the court blocked Trump's efforts to add a citizenship question to the 2020 census, which was opposed by civil rights activists who said the move would dilute the political representation of minority groups including Hispanics.

The arguments come as Trump is attempting to win over Hispanic voters in key states like Pennsylvania. The president's support among the demographic has held relatively steady, around 25%, in the years since he was elected. That has been true despite his harsh rhetoric on immigration and controversial policies such as separating families at the border.