WASHINGTON - US President Barack Obama will offer five million undocumented migrants protection from deportation Thursday, allowing families to come out of the shadows and seek work permits.
In a move that infuriated Obama's Republican critics, the White House said nearly all undocumented people living in country for more than five years and who have a child who is a US citizen or legal permanent resident can apply for three-year work authorization.
The president will also broaden the program he launched in 2012 that provides temporary residency to young undocumented immigrants who arrived in the United States before the age of 16.
Obama's executive order shifts from a dragnet approach to re-prioritizing the deportation focus on convicted felons and those who pose a danger to society It will affect about 44 percent of the 11.3 million people - mostly from Mexico and Central America - living in the shadows.
Those living and working illegally in the country and who meet the criteria can apply for deferred deportation from next spring, the White House said.
For much of this year Republicans have warned that unilateral action on immigration would be an illegal and unconstitutional amnesty of millions of undocumented people.
But Obama shot back, saying he was taking needed action while congressional Republicans dithered.
"Mass amnesty would be unfair. Mass deportation would be both impossible and contrary to our character," Obama said, in excerpts of a primetime speech sent to reporters before he was to deliver it to the nation at 8:00 pm (0100 GMT Friday).
"What I'm describing is accountability - a commonsense, middle ground approach: If you meet the criteria, you can come out of the shadows and get right with the law," he said.
"If you're a criminal, you'll be deported. If you plan to enter the US illegally, your chances of getting caught and sent back just went up." Since 1986, when then-Republican president Ronald Reagan granted a sweeping amnesty, all attempts at major reform of the country's immigration system have failed.
Faced with a congressional stalemate, Obama - who made immigration one of his priorities on taking office in 2009 - has decided, with two years left in the White House, to take the matter into his own hands.
Under the new rules, those applying for deferred action must have a clean criminal record, pass a background check, and pay taxes.
The plan expands the program allowing temporary residency cards for minors to include those of all ages, provided they arrived in country prior to January 1, 2010, instead of the previous date of 2007, and were 16 or younger when they entered.
And it also eases legal immigration rules for high-tech workers and students in "STEM" fields - science, technology, engineering and mathematics.
Obama's order may not, however, provide a clear path to eventual citizenship or permanent residency for migrants, an idea that may have to wait for another president or another generation of lawmakers.
The White House has long sought to pass a broad immigration reform package that would offer a path to citizenship for young migrants that grew up in the United States.
A new immigration law did pass the then-Democratically controlled Senate last year, but the Republican House of Representatives blocked it and failed to agree on its own alternative proposal.
Republicans, who will control both the House and Senate in January after a huge win in this month's midterm elections, say Obama is going too far.
Incoming Republican Senate Majority Leader Mitch McConnell warned Thursday that the new Congress will exact political retribution.
"If President Obama acts in defiance of the people and imposes his will on the country, Congress will act," he said.
"President Obama is not above the law and has no right to issue executive amnesty," Senator Rand Paul added on learning of the plan's details.
"His actions blatantly ignore the separations of powers and the principles our country was founded on." Democrats counter that Republicans have blocked other attempts at reform.
According to an opinion poll by NBC and The Wall Street Journal, 48 percent of Americans disapprove of Obama's immigration plans, against 38 percent who back them.
Storm brewing on Capitol Hill
The political firestorm unleashed by Obama does not bode well for relations between Congress and the White House in coming months.
Republicans cannot block a presidential decree, but they can make Obama's last two years extremely difficult - by blocking his choices to fill ambassadorial and administration posts, as well as judgeships.
But with the 2016 presidential election on the horizon, the debate within the party on immigration will be lively, as Republicans can ill afford to ignore Hispanic voters, 70 percent of whom voted for Obama in 2012.