Jumping ahead of Republicans in Congress, 17 states on Wednesday filed a lawsuit in federal court challenging President Obama's executive action to shield millions of undocumented immigrants from deportation.

Leading the coalition of mostly Republican states is Greg Abbott, governor-elect of Texas who is completing his final weeks as attorney general of the dominant Southern border state. Filed in Texas, the suit charges that Obama is violating his constitutional duty to "take care that the laws be faithfully executed" along with other federal laws. "That unilateral suspension of the nation’s immigration laws is unlawful," the lawsuit said. "Only this court’s immediate intervention can protect the plaintiffs from dramatic and irreparable injuries."

The White House expected a bevy of legal challenges to Obama's action, and the multi-state lawsuit isn't even the first to be filed: Sheriff Joe Arpaio of Maricopa County in Arizona, the famous crusader against illegal immigration, went to court against the president within hours of his prime-time announcement last month. Aides to Speaker John Boehner have also not ruled out a lawsuit on behalf of the House of Representatives, which has already sued the Obama administration over its implementation of the Affordable Care Act. There is also the question of which parties have the legal standing to challenge the decision: While it is common for states, through their attorneys general, to sue the federal government, there is much less precedent for one chamber of Congress to file suit against the executive branch.

Legal scholars have generally backed the administration's argument that Obama's directive falls under the standard of "prosecutorial discretion" that is common in law enforcement, and the White House has cited previous, though more limited, actions taken by presidents of both parties to protect immigrants from deportation. In a rare move, the administration also released a formal opinion by the Office of Legal Counsel asserting that the president was acting within his legal authority.

“The Supreme Court and Congress have made clear that federal officials can set priorities in enforcing our immigration laws, and we are confident that the president’s executive actions are well within his legal authorities," White House spokeswoman Brandi Hoffine said in response to the lawsuit.

Testifying before a House committee on Tuesday, Homeland Security Secretary Jeh Johnson said the administration "spent a lot of time with lawyers" in crafting its policy. "The analysis was very thoughtful, very time-consuming and very extensive," Johnson said. "And I'm satisfied as a lawyer myself, and the person who has to come here and defend these actions, that what we have done is well within our existing legal authority."

Yet in their lawsuit, the states sought to use Obama's own words against him in their argument that he was doing much more than deciding how aggressively to enforce immigration laws. The 75-page documents cites the president's unscripted comments during a rally after his announcement, when he said, "I just took an action to change the law." In that statement, the suit alleges, Obama "candidly admitted that his plan was unilateral legislation."

It may seem far-fetched that a court could throw out a major policy based on a president's offhand remark. But as supporters of the Affordable Care Act are now keenly aware, the future of Obama's signature domestic achievement now hinges on the Supreme Court's interpretation of a four-word phrase in the mammoth law. With Congress seemingly unable to block the administration, those challenging the president's immigration move in court are looking for anything that sticks.