Washington (CNN) President Donald Trump prompted anguish for 800,000 people brought illegally to the US as children by deciding to end a program shielding them from deportation on Tuesday.

But he also triggered swift and sweeping political consequences. By forcing Congress to deal with the issue, Trump piled a new and deeply contentious issue on to the mountain of other politically charged tasks lawmakers were already struggling to deal with in a fateful fall political season.

In many ways, Tuesday's announcement was a signal moment in Trump's presidency: Positions that were once seen as extreme, and coming from the political fringe, came to fruition as policy in deeply divided Washington.

The impact of the President's move is already being felt across the nation, with protests taking place outside the White House, Trump Tower in New York, and around the country. Business leaders have complained the move is unfair and cruel. And former President Barack Obama launched his most comprehensive political intervention since leaving office, saying in a Facebook post that Trump was targeting a vulnerable community that had done nothing wrong.

A case of overreach

Mindful of the political firestorm whipped up by the decision, the White House insisted that Trump had wrestled with the question of the program, known as DACA, but concluded it was an example of overreaching by his predecessor.

Though he fulfilled a promise of a campaign anchored on a hard line on illegal immigration with the move, Trump did not appear in public to announce it himself, perhaps seeking to avoid paying a political price for his action.

Aides said he was not enthused about the decision and he sent his Attorney General Jeff Sessions, who has a long record of seeking tougher enforcement of laws against undocumented migrants, to announce it instead.

But in a statement, Trump insisted that the program, enacted with executive power by Obama after Congress had failed to address the plight of mainly young, undocumented migrants, was illegal.

He also claimed that DACA had spurred a surge of unaccompanied minors to illegally enter the United States, including some who went on to be recruited by gangs, like MS-13.

"As President, my highest duty is to defend the American people and the Constitution of the United States of America," Trump said in the statement.

"At the same time, I do not favor punishing children, most of whom are now adults, for the actions of their parents. But we must also recognize that we are nation of opportunity because we are a nation of laws."

Two officials familiar with the intense West Wing deliberations told CNN that the President asked chief of staff John Kelly to find some kind of middle ground, hoping to put the decision as far away from the Oval Office as possible, and "share the burden" with Congress.

"No one is happy with this outcome -- including the President," one official said, explaining why Sessions was tapped to make the announcement.

Despite his extreme anti-immigration rhetoric during his campaign, Trump has little interest in leading the debate over the legislative fix for DACA, the sources said.

He did not offer lawmakers any guidelines for the kind of legislation he would like to sign.

But his decision sets a clock for Congress to act to preserve the program's protections before the the program's beneficiaries begin losing their status on March 5, 2018.

At best, people affected by the move now face an agonizing wait to see whether Congress can work out a fix allowing them to stay in the US.

If not, hundreds of thousands of people could face deportation from the only country that many of them remember to the nations of their birth.

The Department of Homeland Security will immediately stop processing any new applications for the program but will continue renewing work permits for anyone whose status expires in the next six months.

Trump, who has said that he loves DACA recipients, wrote in a tweet: "Congress, get ready to do your job - DACA!"

All about the base

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The decision appears to be the the latest attempt by Trump, who has seen his approval ratings drop below 40%, to please his loyal political base, a strategy which has included the pardon of former Arizona Sheriff Joe Arpaio and warnings that he may kill off trade deals like NAFTA.

The President may also frustrate some immigration hardliners by building in a six-month delay into the rescinding of the policy to give Congress time to act.

But the prospect of congressional action is complicated by the fact that lawmakers have failed repeatedly to enact meaningful immigration reform during the last two administrations. The task of coming up with protections for DACA recipients could now get mired in the toxic debate around immigration, possibly including the fight over funding for Trump's border wall in a way that could fracture a bipartisan coalition for action.

Dreamers will also be concerned that after registering with the federal government for protection under DACA, officials have detailed documentation on them, that would make it easier to start deportation proceedings.

Obama's long Facebook post called Trump's decision un-American.

"It's a political decision, and a moral question," Obama wrote. "Whatever concerns or complaints Americans may have about immigration in general, we shouldn't threaten the future of this group of young people who are here through no fault of their own, who pose no threat, who are not taking away anything from the rest of us," he wrote.

Other Democrats also slammed Trump.

"President Trump's decision to end DACA is a deeply shameful act of political cowardice and a despicable assault on innocent young people in communities across America," said House Democratic Minority leader Nancy Pelosi.

"Deporting Dreamers means destroying the lives of hundreds of thousands of patriotic young people, costing the economy billions and betraying the fundamental values of the American Dream," she said.

Reaction

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Plans to rescind DACA had been criticized in advance by many prominent business figures, amid concern for DACA recipients in their work forces and warnings about the economic impact of such a move.

Microsoft President Brad Smith said the software giant was deeply disappointed by the decision and called on Congress to act immediately.

"This means that Congress should adopt legislation on DACA before it tries to adopt a tax reform bill. This is the only way, given the number of legislative days Congress has scheduled over the next six months, we realistically can expect Congress to complete DACA legislation in time," he said.

Mark Zuckerberg, the founder of Facebook, said the decision marked "a sad day for our country."

"It is particularly cruel to offer young people the American Dream, encourage them to come out of the shadows and trust our government, and then punish them for it," Zuckerberg wrote.

But Texas Attorney General Ken Paxton, one of the state officials who had pledged to challenge DACA in court praised Trump's move to overturn what he said was an abuse of power by Obama.

"If ever there were a violation of the President's duty to 'take Care that the Laws be faithfully executed,' DACA was it," Paxton said in a statement.

House Speaker Paul Ryan said that though it was well-intentioned, DACA represented an overreach of executive power by Obama.

"It is my hope that the House and Senate, with the president's leadership, will be able to find consensus on a permanent legislative solution that includes ensuring that those who have done nothing wrong can still contribute as a valued part of this great country," Ryan said in a statement.