A U.S. federal judge on Monday temporarily blocked President Barack Obama's plan to protect millions of undocumented immigrants from deportation, an issue likely to be seized upon in the 2016 presidential campaign.
Ruling in favor of about two dozen U.S. states opposed to the plan, U.S. District Judge Andrew Hanen in Brownsville, Texas, said the administration had not complied with procedure.
The White House said the Department of Justice would appeal the decision, which was posted on the Los Angeles Times website.
Obama announced a program in November to lift the threat of deportation from some 4.7 million illegal immigrants using his executive authority. The move bypassed Congress, which has not passed immigration reform legislation despite several attempts.
The program would allow some 4.4 million people whose children are U.S. citizens and legal permanent residents stay in the country temporarily.
Another 270,000 people would be able to stay under the expansion of a 2012 program known as Deferred Action for Childhood Arrivals (DACA) that offered deportation relief to people brought illegally to the United States as children, allowing them work. That expansion was scheduled to begin on Wednesday.
Some 26 states, led by Texas and its Republican governor, Greg Abbott, sued the administration to halt the programs, arguing that Obama's orders violated constitutional limits on his powers. They requested an injunction to block the programs from going into force while the legal process played out.
"Judge Hanen's decision rightly stops the president's overreach in its tracks," said Abbott, who took to Twitter to laud the ruling.
"The president's attempt to by-pass the will of the American people was successfully checked today."
Republicans had said Obama's plan amounted to an essential amnesty for people who entered the country illegally.
Responding to the ruling, the White House said the Supreme Court and Congress had made clear that the federal government can set priorities in enforcing immigration laws, "which is exactly what the President did when he announced commonsense policies to help fix our broken immigration system."
"Top law enforcement officials, along with state and local leaders across the country, have emphasized that these policies will also benefit the economy and help keep communities safe."
Both Democrats and Republicans are likely to seize upon the issue and the court's ruling in the 2016 presidential campaign.
The administration's move had drawn praise from immigrant advocates including Hispanics, who make up a critical voting bloc that has largely thrown its support to Democrats in favor of granting relief to the some 11 million undocumented people.
"We firmly believe that these programs will be implemented, and whether it's now or several months from now, we have no question that the president was well within the bounds of his executive authority," said Melissa Crow, Legal Director of the American Immigration Council group.
"We really feel that this case is more about politics than law," she said.
Barring an unlikely legislative deal in the last two years of his presidency, the executive action would become a key legacy item for Obama, who promised in his 2008 and 2012 presidential campaigns to reform the system.
(Reporting by Jeff Mason, Jonathan Stempel, Chris Michaud and Ted Kerr; Editing by Nick Macfie)