President Barack Obama on Thursday signed into law a set of new measures that will allow millions of immigrants living illegally in the US to apply for work permits, but, in the process, he set himself on a collision course with Republicans in the Congress for announcing unilateral measures.
Under the law, migrants who have lived in the US for at least five years and have not committed a criminal offence will be given work permits and allowed to pay taxes. Their children will also be able to attend school without fear of being found out or deported.
While only parents who have lived in the US for five years will qualify - an estimated four million people, hundreds of thousands more will benefit from other changes, including a decision to broaden a scheme giving temporary legal status to those who arrived in the US as children.
The reform package, forced through using executive orders, which allow Obama to bypass Congress, will benefit nearly five million. Immigration reform was one of President Obama's earliest electoral promises.
Obama said he was forced to use presidential authority to reform America's "broken" immigration system after the Congress failed to pass an immigration reform bill over the past six years.
In a prime-time address to the nation, Obama described his executive actions as a "commonsense, middle ground" approach that walked the line between "mass amnesty... and mass deportation" of an estimated 11 million illegal immigrants in the US.
"Come out of the shadows and get right with the law," Obama said in a televised address.
He insisted that his proposals, which are the biggest immigration reforms since the mid-1980s, did not amount to an amnesty.
"What I'm describing is accountability - a common-sense, middle ground approach," he said.
Although the plan will allow millions to work, it will not offer a path to citizenship or entitle them to the same benefits as Americans, 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," he said.
Republicans reacted with fury, Arizona Republican Senator John McCain calling it an "illegal power-grab" that "fails to address the root causes of the dysfunction in our immigration system".
And Texas Governor Rick Perry argued the move would "lead to more illegal immigration, not less".
An Obama aide rebuffed the criticism, saying the president had taken advice from the secretary of homeland security and the attorney general about the action.
"It's entirely consistent with the way previous presidents have exercised their executive authority," the aide said.
As per 2012 data available with the UD Department of Homeland Security, 59 per cent of illegal immigrants in the US were from Mexico, 6 per cent from El Salvador, 5 per cent from Gautemala and 3 per cent each from Honduras and the Philippines.
Republicans who accused him of acting like "an emperor" and disregarding the Constitution, the Congress and the verdict of American people who handed him a drubbing at this month's midterm elections.
They include immigrants living in the US for five years who have children staying legally in the US.
He's bypassing the legislature and brandishing his big stick - the executive order. It is governance by diktat. And the reaction of his opponents suggests it will spark an atmosphere of retaliation and revenge.
"By ignoring the will of the American people, President Obama has cemented his legacy of lawlessness and squandered what little credibility he had left," said House Speaker John Boehner, R-Ohio. "Republicans are left with the serious responsibility of upholding our oath of office. We will not shrink from this duty, because our allegiance lies with the American people. We will listen to them, work with our members and protect the Constitution."
Barack Obama says he has grown so weary of trying to get Congress to engage seriously that he is going it alone.
The Democrat-led Senate passed the bill, but the Republican-controlled House of Representatives refused to debate the proposal. And, on Thursday, Obama said those who questioned his authority to use executive orders should simply pass the bill.
While campaigners for migrants' rights broadly welcomed Obama's plans, some activists are worried that the promise of a three-year work visa - those given to IT professionals and engineers - would not be enough for many people to come out into the open.
Major policy initiatives usually require an Act of Congress and cannot be introduced through executive orders. President Obama had issued 193 orders in almost six years, much lower compared to many of his recent predecessors.
Franklin D Roosevelt, the most prolific president of all, had issued 3,522 executive orders in eight years.