Republican lawmakers aren't just uneasy about the Obama administration's move to grant a reprieve to thousands of illegal immigrants who came here as children.
Several say they're not even sure it's legal.
Though members of both parties have expressed an interest in crafting legislation to potentially let young illegal immigrants stay in the U.S., Republicans took exception to the Department of Homeland Security's announcement last Friday. Accusing the administration of making an end-run around Congress, GOP officials are increasingly questioning the president's legal authority for the move.
Twenty Republican senators fired off a letter to President Obama on Tuesday asking a string of questions about the legal basis for the policy change.
"Not only do we question your legal authority to act unilaterally in this regard, we are frustrated that you have intentionally bypassed Congress and the American people," Sen. Chuck Grassley, R-Iowa, and the other senators wrote.
House Judiciary Committee Chairman Lamar Smith, R-Texas, followed up with a letter to Obama Wednesday, likewise asking for legal opinions backing up what he described as "amnesty."
Smith wrote that the move "represents a breach of faith with the American people and our Constitution, blatantly ignoring the rule of law and the separation of powers that are the foundations of our democracy."
Other lawmakers have taken their concerns beyond letter-writing.
Rep. Steve King, R-Iowa, told Fox News Radio that he plans to sue. "We have to settle this issue," King said. "And if we don't take a stand here on this issue, then the door's wide open for the president to do whatever he shall do with his presidential edicts."
Rep. Ben Quayle, R-Ariz., earlier in the week introduced a bill to bar the implementation of the policy. Fellow Republican Arizona Rep. David Schweikert introduced a similar measure.
Meanwhile, the president's announcement threw into question an effort by Sen. Marco Rubio, R-Fla., to draft a similar measure -- only in Congress.
Rubio told Fox News on Wednesday that the administration's decision, though, did not strike a balance.
"The biggest problem I have with it is that (Obama) ignores the Constitution and the Congress and shoves it down our throat," the senator said.
Rubio said the Executive Branch decision "sets the whole thing backwards," asserting that the administration has now inserted "election-year politics" into the debate.
The Obama administration unveiled the new policy on Friday. Under the change, the federal government would make certain illegal immigrants eligible for work permits, provided they're under the age of 30 and came to the U.S. before they were 16. They also must not have been convicted of a major crime and must have been continuously living in the U.S. for the past five years.
Obama, in remarks Friday, stressed that the change is meant to help illegal immigrants who came here as children -- many of whom do not even realize they are undocumented "until they apply for a job or a driver's license, or a college scholarship."
Obama stressed his continued support for the legislative proposal, the DREAM Act, which contains similar provisions but has not passed out of Congress. He cast the change by Homeland Security as a temporary solution.
"This is not amnesty, this is not immunity. This is not a path to citizenship. It's not a permanent fix," he said. "This is a temporary stopgap measure that lets us focus our resources wisely while giving a degree of relief and hope to talented, driven, patriotic young people."
But Kris Kobach, the Kansas secretary of state and co-author of several state anti-illegal immigration laws, told Fox Business Network that the administration is "breaking federal law."
He pointed to a section in federal law he says states "very clearly that the president's administration cannot grant this sort of amnesty or cannot refuse to place in deportation proceedings an alien in this situation, who's illegally in this country."