President Obama's executive action preventing the deportation of an estimated 5 million people living in the United States illegally suffered another setback Monday after a federal appeals court upheld a federal judge's injunction blocking the measure.

The 2-1 decision by the 5th U.S. Circuit Court of Appeals in New Orleans further dims the prospect of implementation of the executive action before Obama leaves office in 2017. Appeals over the injunction could take months. Depending on how the case unfolds, the injunction could even go back to the Texas federal court for more proceedings.

Republicans had criticized the plan as an illegal executive overreach when Obama announced it last November. Twenty-six states challenged the plan in court. U.S. District Court Judge Andrew Hanen granted the temporary injunction preventing the order's implementation this past February, agreeing with the states that legalizing the presence of so many people would be a "virtually irreversible" action that would cause the states "irreparable harm."

The administration argued that the executive branch was within its rights in deciding to defer deportation of selected groups of immigrants, including children who were brought to the U.S. illegally.

"President Obama should abandon his lawless executive amnesty program and start enforcing the law today," Texas Gov. Greg Abbott said in a news release.

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The administration could ask for a re-hearing by the full 5th Circuit, but the National Immigration Law Center, an advocacy group, urged an immediate Supreme Court appeal.

"The most directly impacted are the 5 million U.S. citizen children whose parents would be eligible for temporary relief from deportation," Marielena Hincapie, executive director of the organization, said in a news release.

The Justice Department said in a statement that it disagreed with the court's ruling, claiming that Obama's action would "allow DHS to bring greater accountability to our immigration system by prioritizing the removal of the worst offenders, not people who have long ties to the United States and who are raising American children." The statement did not specify what the department's next steps would be.

Part of the initiative included expansion of a program called Deferred Action for Childhood Arrivals, protecting young immigrants from deportation if they were brought to the U.S. illegally as children. The other major part, Deferred Action for Parents of Americans, would extend deportation protections to parents of U.S. citizens and permanent residents who have been in the country for years.

The 70-page majority opinion by Judge Jerry Smith, joined by Jennifer Walker Elrod, rejected administration arguments that the district judge abused his discretion with a nationwide order and that the states lacked standing to challenge Obama's executive orders.

They acknowledged an argument that an adverse ruling would discourage potential beneficiaries of the plan from cooperating with law enforcement authorities or paying taxes. "But those are burdens that Congress knowingly created, and it is not our place to second-guess those decisions," Smith wrote.

In a 53-page dissent, Judge Carolyn Dineen King said the administration was within the law, casting the decision to defer action on some deportations as "quintessential exercises of prosecutorial discretion," and noting that the Department of Homeland Security has limited resources.

"Although there are approximately 11.3 million removable aliens in this country today, for the last several years Congress has provided the Department of Homeland Security with only enough resources to remove approximately 400,000 of those aliens per year," King wrote.

Fox News' Shannon Bream and Matt Dean and The Associated Press contributed to this report.