U.S. President Barack Obama warned governors opposing his move to admit and resettle thousands of Syrian refugees, saying they do not have the power to block the federal government's programme and face punitive action if they persist to do so.

The Republicans immediately denounced the president's warning, calling it "hypocritical" for demanding the governors' obedience to the wishes of the federal government while at the same time ignoring immigration law, WND reported.

Obama's warning, which came in a letter from the Office of Refugee Resettlement (ORR) signed by director Robert Carey, sets the stage for a Tenth Amendment showdown, pitting the states against the federal government.

The letter read, in part: "States may not deny funded benefits and services to refugees based on a refugee's country of origin or religious affiliation. Accordingly, states may not categorically deny ORR–funded benefits and services to Syrian refugees."

States that fail to comply with the federal government would be perceived as law–breakers and "could be subject to enforcement action, including suspension or termination," the letter says.

More than 20 governors mostly from Republican–led states earlier announced that they will not accept not even one of the 10,000 Syrian refugees the Obama administration is set to welcome into the country, expressing concerns for the safety and security of their constituents. Their opposition stemmed from the Nov. 13 terrorist attacks in Paris, and fears that Islamic State (ISIS) militants could use the controversial programme to sneak into the country and sow terror on their constituents.

Virginia's Republican Rep. Bob Goodlatte, who chairs the House Judiciary Committee, supported the governors' action.

"While the United States has the most generous refugee system in the world, the American people are rightly concerned about admitting Syrian refugees and the impact it would have on the safety of their families and neighbours. ... It's hypocritical for Obama administration officials to threaten enforcement action against these states when they refuse to enforce the vast majority of our immigration laws, such as cracking down on sanctuary cities that openly defy federal law and endanger the American people," he said as quoted by Fox News.

Meanwhile, a group of federal law enforcers rejected Obama refugee plan, urging the president to extend care to homeless vets instead, according to the Washington Examiner.

Federal Law Enforcement Officers Association President Nathan Catura said there is no way to check the backgrounds of incoming Syrians for terrorist activities, and that American war veterans are more deserving of the potential billions of dollars that would be used for the refugee programme.

"How would our government distinguish men and women of military age from true refugees with those intending harm to the American public? The hard, cold truth is there is no way to do it," he said in a statement.