President Obama had better think twice if he's considering using an executive order to change how immigration laws are enforced, top conservatives warned on Sunday morning television shows. Obama's long-rumored executive action plan on immigration was leaked to the New York Times Friday, giving Americans a first look at exactly how the president could make it possible without congressional approval for 5 million immigrants to live and work within the U.S..

The notion has infuriated Republican leaders, who have warned the president against acting unilaterally before the GOP officially takes control of the Senate and House of Representatives in January. That frustration was evident Sunday when former Republican presidential candidate Mitt Romney, conservative columnist George Will and others appeared on television to admonish the president for considering such a maneuver.

“The American people sent a very clear message to the president about his policies: They're not happy with them,” Romney told CBS' "Face The Nation." “Let the Congress, let the election have its say as opposed to jumping in and, by doing something unilaterally and in a way that is extra-constitutional, he is poking an eye of the Republican leaders in Congress.”

Romney did not elaborate on what he meant by “extra constitutional." The 2012 presidential candidate and former governor of Massachusetts wasn't alone in his criticism. Former Washington Post columnist George Will also weighed in on the issue during an appearance on Fox News Sunday, though he took a softer line on the immigration issue.

“The policies are defensible,” Will said of a proposal to eliminate a mandatory fingerprinting system for immigrants, an expansion of the DREAM Act, and relief for the undocumented parents of U.S.-born children. “The policies are execrable. There's a simple etiquette to democracy.”

Will also expressed disappointment Obama seems to have departed from his criticism of U.S. President Bush and Vice President Cheney's “expansive use of executive power.”