The Obama administration has taken the biggest step towards granting legal status to undocumented immigrants in America in 25 years by ordering the end to deportations of law-abiding young people who came to the US as children.
Announcing the change in the Rose Garden of the White House on Friday, Obama said that it would remove the fear of deportation from young people known as Dreamers. "These are young people who study in our schools, play in our neighbourhoods, pledge allegiance to our flag. They are Americans in their heart and minds, and in every single way but one: paper."
The dramatic shift gives about 800,000 people the chance of gaining temporary legal status to live and work in the US That makes this the most dramatic shift since Ronald Reagan granted an amnesty to 3 million largely Hispanic undocumented immigrants in 1987.
In a country sharply divided over what to do with the millions of people living illegally in the country, the controversial nature of the announcement was underlined by a heckler, later revealed to be Neil Munro of the the rightwing blog the Daily Caller, who broke into Obama's address. The president, clearly furious, berated Munro for interrupting him.
The president went on to say: "Put yourselves in [the Dreamers'] shoes. Imagine you've done everything right your entire life, only to suddenly face deportation to a country you know nothing about with a language that you do not speak."
Obama added that it made no sense to deport young people who were making an extroardinary contribution to the US economy.
The move was hailed by Latino and civil rights groups across America. "This is hugely important for undocumented immigrant youths who were brought to the US as kids and didn't have any say in the matter. Obama has finally acted on an issue that has festered far too long," said Clarissa Martinez-de-Castro of the largest Latino civil rights group in America, the National Council of La Raza.
Laura Murphy of the American Civil Liberties Union said: "The administration has provided these young adults the opportunity to pursue the American Dream."
The order also has great political significance, just five months before a presidential election that could hang on the outcome in a handful of key swing states with large Latino populations. There has been mounting frustration within Hispanic communities in recent months over Obama's perceived failure to deliver on his promise to reform the country's broken immigration system, and this could reignite his base.
It also has the advantage of putting his rival for the presidency, Mitt Romney, in a political bind. Romney knows that he has to win Latino support if he is to take the White House. But he cannot afford to alienate those right-wing Republicans he wooed during the primaries by adopting the hardest line on immigration of any conservative candidate.
The end to deportations for young undocumented immigrants was portrayed by the White House as a change to the immigration procedures - a clever move that bypasses the Republican-controlled House of Representatives that has blocked all reform on this issue. The order does nothing to answer the long-term conundrum, as only Congress can pass the "Dream Act" that would provide young Hispanics with a pathway to citizenship.
In his address, Obama said that he would continue to press for a long-term solution through Congress in the form of the Dream Act. "As long as I am president I will not give up on this issue - it's the right thing to do, period."
But his temporary rule change does at least remove the pall of deportation hanging over young undocumented Latinos. The new guidelines will apply to any unauthorised immigrant who is aged between 16 and 30; who came to the US as a child; who has no criminal record; and who has lived continuously in the country for at least the past five years.
Anyone who meets the criteria can apply for "deferred action" that will remove them from threat of deportation for a renewable two years. They can then apply for a work permit, bringing them out of the shadows and openly into the American workforce.
Though Romney could overturn the guidelines were he to win the presidency in November, immigration experts predicted that it would be politically difficult for him to do so. "Once one million young and talented people start getting their doctorates, taking up positions in business and the military, even Mitt Romney would be foolish to try and unpick this," said Frank Sharry, director of the immigration reform campaign America's Voice.
Coming just a month after Obama threw his weight behind gay marriage, there was inevitable speculation that the move was politically motivated. "This is a blatant political decision by Obama," said Ana Navarro, who was John McCain's national Hispanic chairperson during the 2008 presidential race.
Navarro pointed out that the announcement was made just days before Obama addresses Latino conferences in Florida and Nevada – two battleground states with large Hispanic populations. "The timing is no coincidence," she said, adding that the announcement posed Romney with a serious political challenge. "Romney needs to tread very carefully here – the Dream kids are a popular cause with the Hispanic community and he makes a mistake if he shows no sympathy for them."
Marco Rubio, the Latino Florida senator who is a leading contender to be Romney's vice-presidential running mate, gave a nuanced response. He said he supported help for undocumented children but criticised the order as a "short-term answer to a long-term problem".
The difficulties that Romney faces were underlined by the fact that it took him five hours to respond to the Obama announcement. After a campaign stop in New Hampshire, the Republican nominee-in-waiting eventually said: "I think the action that the president took today makes it more difficult to reach that long term solution."
Romney's cautious reaction echoed almost to the word that of Rubio, which was paradoxical given that the two Republicans have been at opposite ends of the conservative debate on immigration. Rubio in recent weeks has been gathering support for a compromise version of the Dream Act that would give young undocumented Latinos a path to citizenship.
Romney by contrast has supported "attrition by enforcement" - the idea of making life so uncomfortable for illegal immigrants that they choose to leave the country. One of his immigration advisers, Kris Kobach, told the Guardian earlier this year that Romney would impose the policy nationwide were he elected president .
Yet in his response to the Obama order, Romney went as far as to say he agreed with Rubio. Though he did not mention the Dream Act by name, Romney said: "I happen to agree with Marco Rubio as he looked at, considered this issue."
Latinos, who make up about 80% of America's 11m undocumented immigrants, are an increasingly important section of the electorate. The number of eligible Hispanic voters has grown from 13 million in 2000 to 21m in 2010.
Their political significance is amplified by the fact that their presence is concentrated in battleground states where the presidential election will be lost or won, such as Colorado, New Mexico, Nevada, Florida and Virginia.
George Bush held onto the White House in 2004 with 44% of the Hispanic vote. But as the party has moved to the right, its standing with Latinos has suffered: in 2008 Latino backing had slipped back to 31% for McCain, and could fall further as a result of Romney's harsh pronouncements on "self-deportation" during the primaries.
But anger had also been bubbling away within Hispanic communities over lack of action within the White House. Obama's lack of action until now, and the surge of deportations under him to record levels, has led to signs of apathy among Democratic-leaning Hispanic voters.