WASHINGTON — President Obama will ask the Supreme Court to clear the way for his far-reaching overhaul of the nation’s immigration system, administration lawyers said Tuesday, setting up a battle in the nation’s highest court over whether nearly five million undocumented immigrants can legally live and work in the United States.

A year after the president asserted the power of his office to provide work permits and protection from deportation for those immigrants, his plan remains under assault by conservatives who have tied it up in legal limbo. On Monday, a federal appeals court said the president had exceeded his authority.

If the Supreme Court agrees to hear the president’s case during the current term, a ruling could come by next summer, just days before the two political parties hold their nominating conventions for the 2016 presidential campaign. A June decision could ensure a fierce debate on an issue that is critical to partisans on both sides.

“This is the moment that we, along with millions of families, have been waiting for,” said Marielena Hincapié, the executive director of the National Immigration Law Center. “We are more than ready to take this case to the Supreme Court.”

 

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A decision by the court would also have a long-lasting impact on the president’s legacy, shaping how future generations assess Mr. Obama’s ability to confront what he has called one of the generation’s great civil rights issues. And it would mark the latest test of Mr. Obama’s agenda, after Supreme Court rulings on women’s rights, health care, the environment and the exercise of presidential power.

Legal experts said that no matter how the court ruled, the decision from the justices could expand or trim the executive authority of future presidents on issues well beyond immigration policy. Walter Dellinger, an acting solicitor general in the Clinton administration, said a ruling against Mr. Obama would scale back presidential power for generations.

That could put the United States “down a road of vastly increased judicial determination of basic policy questions,” Mr. Dellinger said.

Reaction from the presidential candidates on Tuesday was swift, and underscored the political clash to come. Ted Cruz, a Republican senator from Texas, said in Twitter that the appeals court ruling was a victory in the fight against “Pres. Obama’s illegal & unconstitutional executive amnesty.”

Hillary Rodham Clinton assailed what she called a “politically motivated” lawsuit against the president’s actions, and she called on the court to provide a fair hearing “so that the millions who are affected can stop living in fear of their families being broken apart.”

Frank Sharry, the executive director of America’s Voice, an immigrant advocacy group, and a supporter of the president’s actions, said the choice for voters on immigration could not be more starkly on display. He and other rights activists said the case could help Democrats in 2016 appeal to Latino voters.

“All Democrats promise to defend and expand on Obama’s executive actions, and all Republican contenders promise to do away with Obama’s executive actions,” Mr. Sharry said. “However they decide it will likely galvanize Latino voters, who overwhelmingly support these executive actions.”

The United States Court of Appeals for the Fifth Circuit said in its ruling on Monday that the immigration program set up by the president’s actions — known as Deferred Action for Parents of Americans — did not follow proper administrative procedures and went beyond the power that Congress has authorized for a president.

The Justice Department said in a statement on Tuesday that it would appeal the decision by the lower court that blocked Mr. Obama’s executive actions.

“The Department disagrees with the Fifth Circuit’s adverse ruling and intends to seek further review from the Supreme Court of the United States,” said Patrick Rodenbush, a spokesman for the Justice Department.

That review by the Supreme Court is not a foregone conclusion. Monday’s ruling by the appeals court was issued at a preliminary stage of the litigation, and the Supreme Court sometimes prefers to await a final ruling. The justices may have their own reasons to move at a deliberate pace even if they ultimately vote to hear the case.

But Mr. Dellinger said there was no impediment to prompt review, and he predicted that the Supreme Court would act. He pointed out that although overlapping three-judge panels of the Fifth Circuit had twice ruled against the administration, the administration had in one sense gotten a split decision — altogether, two judges had voted for it and two against.

“I think the Supreme Court will hear this case,” Mr. Dellinger said, adding that he expects a victory for Mr. Obama in his appeal of the losses in the lower courts. “I have every reason to expect that the U.S. Supreme Court will reverse this ruling.”

Even if the Supreme Court takes Mr. Obama’s side in the case, it will leave the president very little time to carry out the program and sign up millions of undocumented immigrants in the last few months of his presidency. If a Republican is elected in 2016, that could mark the end of Mr. Obama’s efforts to shield the immigrants from deportation.

Greg Abbott, the Republican governor of Texas, which led the 26-state coalition that filed the lawsuit against the president’s actions, called the lower court decision a “vindication for the rule of law and the Constitution.”

“The president’s job is to enforce the immigration laws, not rewrite them,” Mr. Abbott said. “President Obama should abandon his lawless executive amnesty program and start enforcing the law today.”

The White House’s press secretary, Josh Earnest, expressed confidence in the administration’s lawyers and accused the Republican Party of standing in the way of needed changes to immigration laws.

“It results in more families being torn apart,” Mr. Earnest said. “And that is clearly not in the best interest of our national security; it’s not in the best interest of public safety. It is also not consistent with the values of this country.”

But regardless of what the court might decide, activists on both sides said Tuesday that they were ready to take the issue to voters during next year’s presidential campaign. Yanely Gonzalez, a 17-year-old American citizen whose parents would qualify for protection under Mr. Obama’s plan, pledged to vote for “the candidate who treats my family and my community with respect.”

Rocio Saenz, the executive vice president at the Service Employees International Union, predicted that her organization’s membership would rally behind the president’s immigration actions.

“We will continue to defend them on the streets and at the ballot box,” she said, criticizing the Republican assault on the immigration changes. “It is inexcusable. And you better believe, we won’t forget.”