The Trump administration will end an Obama-era program allowing undocumented immigrants brought to the country as minors to remain in the United States, Attorney General Jeff Sessions announced Tuesday.

The administration will “wind down” the Deferred Action for Childhood Arrivals, or DACA, program, which protects about 800,000 undocumented immigrants nationwide from deportation, including nearly 100 Maine residents who U.S. Rep. Chellie Pingree, D-Maine, said will be affected immediately by the decision.

Sessions called the program an unconstitutional overreach of executive power during a Tuesday morning press conference, but the administration is giving lawmakers a window to replace DACA with protections that have congressional support before the program expires in six months.

The announcement followed months of indecision from President Donald Trump, who promised to rescind DACA on the campaign trail but later suggested that people who are protected by it should “rest easy.”

Uncertainty over the program struck fear into so-called “dreamers,” one of whom told the Bangor Daily News in June that waiting for Trump to decide has been “like being a little kid afraid of the dark, wrapped in a blanket waiting for a monster to come, waiting for the sunlight.”

The Department of Homeland Security, which administers DACA, will no longer accept new applications for status under the program, which has provided renewable work permits and Social Security numbers to dreamers across the country since it was enacted by the Obama administration in 2012.

The agency said that those now enrolled in the program will be able to continue working until their permits expire, and that those whose permits expire by March 5, 2018, will have the chance to apply for two-year renewals as long as they do so by Oct. 5.

Former DACA recipients whose work permits have expired will be subject to deportation but will be low priorities for immigration enforcement, according to administration officials.

All four members of the Maine Congressional delegation called for lawmakers to enact protections for the people who will be exposed to deportation by Trump ending the federal program.

Pingree said that Trump’s decision was “irresponsible and inhumane,” adding that it is now up to lawmakers to “clean up” the president’s “mess.” While Rep. Bruce Poliquin, a Republican representing Maine’s 2nd Congressional District, echoed the Trump administration’s sentiment that President Obama had overreached in creating the program, he added that law-abiding dreamers “should be protected from deportation through legislative action by Congress.”

Likewise, Sen. Angus King, an independent, said that he’s disappointed with Trump’s decision but optimistic that Congress will find a “long-term legislative solution.” And Sen. Susan Collins, a Republican, said that Congress “must act quickly to protect those who were brought to the U.S. as children [and] in many cases know only our country as home.”

“It is not right to hold children responsible for the actions of their parents,” Collins, a Republican, said on Twitter.

Trump’s decision was also decried by Maine Attorney General Janet Mills, a Democrat who is seeking her party’s nomination for governor.

Although the vast majority of immigrants in Maine entered the country legally, since DACA’s inception, U.S. Citizen and Immigration has approved 429 applications and reapplications for status under the executive action in the state.

And over the past year, the seven colleges in the University of Maine System all began offering in-state tuition to DACA recipients who are qualified Maine residents.

Last school year, 13 of the roughly 29,000 students in those schools told the administration that they had DACA status, according a spokesman.

In response to the Tuesday’s announcement, University of Maine System Board Chairman James Erwin said that the schools will be “monitoring any congressional proposal to change existing federal immigration standards that may impact the system’s non-citizen students.”

“We are … hopeful that Congress will act to bring certainty to the immigration status of those who seek to better themselves by lawfully pursuing a Maine public higher education and the resulting credentials and degrees that open the door to employment opportunities in our state,” Erwin said in a statement.

Reuters contributed reporting.