The Supreme Court seems 'deadlocked' over one of Obama's signature actions - and it could mean a big defeat

The Supreme Court appeared "deadlocked" over President Barack Obama's plan to provide work permits to millions of immigrants who are in the country illegally, multiple outlets reported.

The Supreme Court heard the challenge to Obama's signature immigration-related actions Monday, in what is one of the most closely watched cases of its term.

The apparent split could mean a defeat for the president on the issue. A 4-4 tie vote would leave in place the decision of the lower court in the case, United States vs. Texas. That decision blocked the implementation of the actions, which would shield millions of people from deportation.

One vacant seat is open on the court after the recent death of the late Justice Antonin Scalia.

Conservative Justice Anthony Kennedy and Chief Justice John Roberts, one of whose votes the Obama administration would likely need to prevail in the case, "sharply questioned" the administration's attorney, according to The Los Angeles Times.

"Kennedy said Congress, not the president, had the authority to decide which groups of immigrants could stay lawfully in the United States," the paper reported.

"It is a legislative act, not an executive act," Kennedy said, according to The Times.

Obama's executive actions, proposed in 2014, aimed to focus deportation efforts on criminally engaged immigrants who are in the country illegally, while providing relief to those who are law-abiding and meet certain qualifications.

Soon after, lawyers representing Texas and 25 other Republican-led states filed a suit in federal court in Brownsville, Texas. Those states claimed the costs of issuing state identification cards to the immigrants would be a heavy burden. A US district judge sided with the states, saying they had the standing to sue the federal government. That decision was upheld in the US Court of Appeals for the Fifth Circuit last year.

Kennedy, a typical swing vote on the high court, seemed to side with the states' argument, The Hill reported.

"It seems to me that's a legislative, not an executive task," he said. "It's as if the president is setting the policy and the Congress is executing it. ... That seems upside down."

Proponents of the actions, however, expressed encouragement following the oral arguments. Todd Schulte, the spokesman for a pro-immigration reform group founded by Facebook CEO Mark Zuckerberg, said the US made "an incredibly strong case."

"We are confident that with the law, the Constitution, and long-standing precedent on our side - including every President in the last 4 decades having used the prosecutorial discretion granted to him by Congress - the Court will uphold President Obama's executive actions on immigration," Schulte said in a statement.

"We will continue working to pass a permanent legislative solution," he continued. "In the meantime, we hope the Court will quickly cement these vital programs to help millions of American families live free from the fear of deportation."