WASHINGTON, Nov. 21 (Xinhua/Sun) -- U.S. President Barack Obama's presidential order on immigration is stirring much controversy, with outraged opponents accusing him of acting more like an emperor than the head of the world's oldest democracy.

In a nationally televised address Thursday night, Obama said he would shield 5 million illegal immigrants from deportation, saying the actions he is taking "are not only lawful, they're the kinds of actions taken by every single Republican president and every Democratic president for the past half-century."

"To those members of Congress who question my authority to make our immigration system work better, or question the wisdom of me acting where Congress has failed, I have one answer: Pass a bill," he said.

Obama announced his plans to go solo after his party was trounced in this month's midterm Congressional elections, which saw the biggest Republican sweep since World War II. In what critics billed as thumbing his nose at voters' decision to reject Democrats' policies, he gave Republicans an ultimatum: either fix the nation's broken immigration system, or he would act unilaterally.

But critics are shouting over what they call flouting the Constitution in an unlawful sidestep of Congressional authority, accusing Obama of overstepping his legal limits as president.

Critics note that Obama has on multiple occasions spoken out in favor of the rule of law in the United States, saying he would not act alone on immigration.

In February last year, Obama said he was "not the emperor of the United States," saying it was unlawful to change immigration law using an executive order. In an interview with a Spanish language news outlet a month earlier, he said "I'm not a king," and explained why he is "required to follow the law."

Those comments coupled with Obama's executive order sparked a response from The Washington Post's fact checkers, who rated the honesty of his statements with an "upside down Pinnochio" -- the lowest rating possible, indicating a blatant flip-flop.

In a statement after Obama's speech concluded, House Speaker John Boehner said that by "ignoring the will of the American people, President Obama has cemented his legacy of lawlessness and squandered what little credibility he had left."

Rising Republican star Senator Rand Paul said in a statement he "will not sit idly by" and allow Obama to "bypass Congress and our Constitution."

"President Obama is not above the law and has no right to issue executive amnesty. His actions blatantly ignore the separations of powers and the principles our country was founded on. The president has said 22 times previously that he does not have the power to legislate on immigration," he said.

But some experts said Republicans may be stuck with the measure.

"Republicans don't have good options on Obama's executive order. They can't repeal it because many presidents have exercised administrative discretion on immigration," Brookings Institution's senior fellow Darrell West told Xinhua.

"Where congressional Republicans have some leeway is on funding the immigration agency. They could pass a bill withholding money from it. But Obama surely will veto that legislation and it is not clear that Congress has the votes to override a presidential veto," West said.

"I don't believe Republicans want to close down government over this issue although some of its members will talk about doing that," he said. "When all the dust settles, I expect the executive order to stick."

The order may shore up the Democratic Party's popularity with Latinos, a crucial constituency in an increasingly multicultural America. "Latino voters will be very happy that Obama has taken a lot of political heat on an issue they really care about. This will help Democrats in 2016," he said, referring to the next race for the White House whereby both parties will compete for the Latino vote.

That will put pressure on Republicans to appeal to Latino voters, many of whom feel disconnected from the Republican Party, viewing it as one of old, white men out of tune with minority voters.

Meanwhile, other critics believe the measure will cause illegal immigration to swell to new highs, as it will send a message worldwide that one can enter the United States illegally and eventually be permitted to stay.

Aside from illegal entry over the U.S.-Mexico border, migrants from Cuba have surged to the highest level in five years, as many arrive in rickety, make-shift boats and rafts -- sometimes 30 people in one small, unsteady vessel.