Attorney General Jeff Sessions and acting Homeland Security Secretary Elaine Duke formally announced that President Donald Trump will end Deferred Action for Childhood Arrivals. The DACA program will not be fully rescinded for six months, effectively forcing on Congress the final say over whether to provide a long-term fix that would stave off deportation for immigrants brought to the U.S. illegally as children.

Introduced in 2012 as a stop-gap measure, the program had allowed people who had arrived in the country at age 16 or youngerto obtain two-year work permits and a reprieve from deportation.

It was instituted in the wake of a pair of high-profile failures by Congress to overhaul the nation’s immigration system, stoking fierce criticism by conservative Republicans and immigration hard-liners that DACA amounted to executive overreach – including from Sessions, a former Republican senator from Alabama, who lambasted DACA in announcing its end Tuesday in remarks at the Justice Department.

“This policy was implemented unilaterally to great controversy and legal concern after Congress rejected legislative proposals to extend similar benefits on numerous occasions to this same group of illegal aliens,” the attorney general said. “The executive branch, through DACA, deliberately sought to achieve what the legislative branch specifically refused to authorize on multiple occasions. Such an open-ended circumvention of immigration laws was an unconstitutional exercise of authority by the executive branch.”

The letter set a deadline of Tuesday to act. The states had previously sued to challenge a companion program, Deferred Action for Parents of Americans, or DAPA, a program that a federal court blocked in 2015.

“Our collective wisdom is that the policy is vulnerable to the same legal and constitutional challenges that the courts recognized with respect to the DAPA program, which was enjoined on a nationwide basis in a decision affirmed by the 5th Circuit,” Sessions said. “If we were to keep the Obama administration’s executive amnesty policy, the likeliest outcome is that it would be enjoined just as was DAPA.”

The attorney general did not take questions at the briefing.

Under the guidance issued by the Justice Department and Department of Homeland Security, DHS agencies that oversee immigration enforcement will immediately stop considering any new DACA applications.

However, those currently enrolled in DACA whose benefits are set to end within the six-month period that ends March 5, 2018, have a one-month period to apply for renewal ending Oct. 5.

Additionally, people who have already submitted an application – either to obtain new DACA status or to have their current benefits renewed – will have their paperwork considered on a case-by-case basis, DHS officials said. All other applications will be rejected.

The president’s decision to end DACA has stoked fears of a crackdown on those enrolled in the program. Applicants are required to submit a raft of personal information to authorities and attest that they are in the country illegally, which has spurred some advocates to question whether Immigration and Customs Enforcement officers will now simply turn to the records they already have on hand to track down people for deportation.

However, the official added that such requests would likely be reserved for higher priority cases, such as when ICE officers are searching for people accused of felonies, serious misdemeanors or when they pose a potential threat to national security, as opposed to simply losing their DACA status.

“Out of all the people that we are targeting in the cases that we are working, that’s a very baseline charge. And with our limited resources, we’re usually focused on higher level targets,” the official said.

That said, the official continued, “I think the thing that they should focus on is following the instructions that have been put out here today and that have continued to be put out by USCIS and go from there.”

A broad range of groups and lawmakers, including some Republicans and the U.S. Chamber of Commerce, lambasted the administration’s decision to rescind DACA, portraying it as a betrayal of trust for immigrants who volunteered their information to authorities.

“President Trump’s action today is an affront to who we are as Americans,” Sen. Kirsten Gillibrand, D-N.Y., said in a statement. “He is needlessly targeting children who know no other country as home than America. This does not make our communities safer or our economy stronger. In fact, it does just the opposite.”

Nonetheless, Sen. Lindsey Graham, R-S.C., and Sen. Dick Durbin, D-Ill., announced plans to hold a press briefing to promote their immigration bill hours after Sessions’ remarks Tuesday afternoon. The House passed a version of the so-called DREAM Act in 2010, but it stalled in the Senate, falling eight votes shy of the 60 needed to pass.

Texas Attorney General Ken Paxton, a Republican who led the coalition of states that threatened to expand its lawsuit to halt DACA, said he was pleased with the Trump administration’s decision.

“I applaud President Trump for phasing out DACA. As the Texas-led coalition explained in our June letter, the Obama-era program went far beyond the executive branch’s legitimate authority,” Paxton said in a statement. “Had former President Obama’s unilateral order on DACA been left intact, it would have set a dangerous precedent by giving the executive branch sweeping authority to bypass Congress and change immigration laws.”

Nonetheless, while the president’s decision may have staved off one court challenge, others appear to be on the horizon: New York Gov. Andrew Cuomo and state Attorney General Eric Schneiderman, both Democrats, have said that New York will sue to stop DACA from being rescinded.