Donald Trump and Ted Cruz insist they’d deport the 11 million immigrants who are in the U.S. illegally. That’s giving the Supreme Court reason to tread carefully when it takes up President Barack Obama’s plan to keep as many as 5 million of them here.

Even before Justice Antonin Scalia’s death two months ago, the November election made the case a tricky one, threatening to put the court into a “political maelstrom,” according to a brief filed by former U.S. Solicitor General Walter Dellinger in support of the administration.

The remaining eight justices hear arguments Monday on Obama’s plan. The case may inflame an already hot campaign topic, and the election creates the possibility that a Republican president Trump or Cruz could cancel the policy even if the Supreme Court upholds it.

The administration is trying to overturn a federal appeals court ruling that blocked the plan on a 2-1 vote. Texas and 25 other mostly Republican-led states say Obama overstepped his authority when he announced the executive action in 2014 amid a stalemate in Congress over efforts to overhaul the nation’s immigration laws.

“We don’t think he has the authority to come in and change the law,” Texas Attorney General Ken Paxton said in an interview. “That’s fundamentally the issue in the case.”

Scalia Vacancy

The prospect of an extended vacancy on the court after Scalia’s death has only increased the political significance. The court could reach a 4-4 deadlock that would uphold the lower court ruling without explanation. That outcome would mark a new level of judicial dysfunction, effectively killing a major presidential initiative without the Supreme Court ever issuing a definitive ruling.

With the stakes so high, advocates on both sides are suggesting narrow approaches that might produce a majority opinion.

The most prominent is the administration’s argument that the states lack the legal standing to challenge the program at all. The Supreme Court has required litigants to show that a challenged government program has injured them in some concrete way.

The appeals court said Texas could sue because Obama’s program would cost the state millions of dollars as people who receive deferred-deportation status become eligible for state-subsidized driver’s licenses.

Supporters of the administration say that’s a self-imposed cost. The state could avoid it simply by decoupling the subsidies from federal immigration classifications, Dellinger said in an interview.

There is “no reason to think Texas would be unable to change their policy,” said Dellinger, whose brief urged the court to throw out the case on grounds that Texas didn’t have the right to sue.

That argument may hold appeal for Chief Justice John Roberts, a potential swing vote in the case and perhaps the court’s staunchest proponent of strict requirements for legal standing.

Texas and its fellow states say the court has never thrown out a case because a litigant could take steps to avoid the injury.

They also point to a 2007 Supreme Court decision that let Massachusetts and other states challenge the Environmental Protection Agency’s refusal to consider regulating greenhouse-gas emissions. In a 5-4 ruling along ideological lines, the court said states are “entitled to special solicitude in our standing analysis.”

Formal Rulemaking

Opponents of the administration are offering their own way for the court to avoid deciding the most controversial questions. They say that under federal law, the Department of Homeland Security should have treated the plan like a formal rule and given the public a chance to comment before finalizing it.

A decision throwing out the plan for that reason would leave room for the Obama administration — or the next president — to revive it by following the rulemaking procedure.

Under Obama’s plan, known as DAPA, people whose children are either U.S. citizens or legal permanent residents, and who meet other requirements, could get relief from deportation for three years plus the right to apply for work permits. Those people, who are primarily from Mexico and Central America, wouldn’t be given an easier path to citizenship.

Texas and its allies say that federal statutes set detailed criteria for determining which immigrants are in the country legally and that those laws don’t let the president shield such a large category of people from deportation. The president says the program is simply a broader exercise of his accepted power to set priorities in deciding who should be deported.

Sixteen other states and the District of Columbia are supporting the administration. The justices will also hear arguments from a lawyer representing the House of Representatives, which voted to file a brief urging the court to throw out the Obama plan.

‘Faithfully Executed’

When it agreed to take up the case in January, the court opened the possibility of a broader ruling curbing the president’s constitutional powers. The justices said they would consider Texas’s argument that Obama violated his constitutional duty to “take care that the laws be faithfully executed.”

Scalia’s death changed the math, making it impossible for Texas to win a sweeping ruling restricting presidential power without the unlikely support of one of the court’s four Democratic appointees.

Although a 4-4 split would block the plan, probably until Obama leaves office in January, it wouldn’t definitively resolve the underlying issues. Proponents of the plan could try to re-open the issue by filing suit in a different part of the country, said Brianne Gorod, chief counsel of the Constitutional Accountability Center, which is backing the administration in the case.

“A 4-4 decision would leave a very complicated and confusing scenario in place,” Gorod said. That “is just one more reason why it is very unlikely that his court is going to end up splitting 4-4.”

Republican President

A victory for the Obama administration would also leave uncertainty. A Republican could win the presidential election, rescind Obama’s plan and begin aggressively deporting unauthorized immigrants.

People who received deferred-deportation status under Obama might be especially vulnerable because they would have supplied identifying information to the government. For that reason, advocates on both sides say few people might apply for deferred-deportation status until after the election.

The policy “really hinges on the outcome of the next election,” said Josh Blackman, a professor at the South Texas College of Law, who filed a brief backing Texas.