Updated 11:24 a.m. | President Donald Trump, answering pleas from his base but again breaking with many congressional Republicans, on Tuesday ended Barack Obama’s program that shielded from deportation individuals who came to the United States with their parents before their 16th birthday.

“The policy was implemented unilaterally,” Attorney General Jeff Sessions said Tuesday while making the formal announcement, referring to then-President Barack Obama implementing the program via an executive order. Sessions called the Obama-era program “unconstitutional.”

“In other words, the executive branch, through DACA, essentially sought to achieve what the legislative branch refused to authorize on a number of occasions,” he said, adding his Justice Department concluded it was unable to defend the DACA program because it was “inconsistent with the Constitution’s … separation of powers.”

“Ending the previous administration’s disrespect for the legislative process is an important first step,” Sessions said.

The immigration program “contributed to a surge of minors” coming across America’s southern border,” a development the AG said spawned “terrible” consequences across the country. During brief remarks, he contended the Obama program put the country at greater risk of “crime, violence and terrorism.”

Trump has ordered DHS officials to cancel Obama’s memo creating DACA and begin an unspecified period of time during which the program will be ended. That span is intentionally designed to give Congress time to craft legislation addressing the Dreamers who have been shielded by Obama’s program.

“We firmly believe this is the responsible path,” the AG said.

Trump’s much-anticipated decision puts pressure on Congress to act immediately, after spending years largely avoiding the issue. The president and his senior aides ultimately, after months of internal administration debate, decided to delay enforcement of his decision by six months so Congress can work with him toward the kind of legislative solution many GOP members are calling for.

“Congress, get ready to do your job – DACA!” the president tweeted a few hours before his decision was formally rolled out.

Congress, get ready to do your job – DACA!

— Donald J. Trump (@realDonaldTrump) September 5, 2017

Some of his top aides have for months urged Trump to nix deportation relief and work permits for around 800,000 people enrolled in the 2012 Deferred Action for Childhood Arrivals program, known as DACA. After months of internal West Wing debate, the president decided to do so.

The Obama-era program had protected certain unauthorized immigrants from deportation and allowed them to work if they came to the U.S. before turning 16 and before June 15, 2007.

Despite ending the program being a major theme of his 2016 campaign, the president did not make the announcement himself. Instead, he tapped Sessions to do the honors. By calling on Congress to act and sending out his AG to announce his decision, the president appeared to be distancing himself a bit from the eventual outcome — and preparing to blame lawmakers if they cannot get a bill to his desk to address the plight of the Dreamers.

As a candidate, Trump said he would end the DACA program, which conservatives consider an illegal amnesty program that circumvents congressional authority. But he has expressed sympathy for Dreamers since his inauguration and admitted thousands of new beneficiaries.