WASHINGTON

President Trump on Tuesday scrapped an Obama era program that protects from deportation immigrants brought illegally into the United States as children, delaying implementation until March and giving a gridlocked Congress six months to decide the fate of almost 800,000 young people.

As the so-called Dreamers who have benefited from the five-year-old program were plunged into uncertainty, business and religious leaders, mayors, governors, Democratic lawmakers, unions, civil liberties advocates and former President Obama all condemned President Trump’s move.

The action was announced on behalf of President Trump, by U.S. Attorney General Jeff Sessions, who called the Deferred Action for Childhood Arrivals program an unconstitutional overreach by former President Obama. There will be an “orderly, lawful wind-down,” Mr. Sessions said.

President Trump later issued a written statement saying, “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 (a) nation of opportunity because we are a nation of laws.”

He denounced President Obama’s program as an “amnesty-first approach” toward illegal immigrants and pressed his nationalist “America First” message, saying that despite concerns voiced by his critics about the fate of the Dreamers, “Above all else, we must remember that young Americans have dreams, too.”

On Tuesday evening, the Republican president tweeted that lawmakers now had six months to “legalize DACA” and that if they did not, he would “revisit this issue!”

Former President Obama issued his own statement, calling President Trump’s action a political decision, defending DACA’s legality and urging Congress to protect Dreamers.

“This is about young people who grew up in America — kids who study in our schools, young adults who are starting careers, patriots who pledge allegiance to our flag. These Dreamers are Americans in their hearts, in their minds, in every single way but one — on paper,” President Obama said.

The Trump administration said nobody covered by the program, which provided work permits in addition to deportation protection and primarily benefits Latinos, would be affected before March 5. Most people covered by DACA are in their 20s.

President Trump shifted responsibility to a Congress controlled by his fellow Republicans and said it was now up to lawmakers to pass immigration legislation that could address the fate of those protected by DACA who would be in danger of deportation.

President Trump and Mr. Sessions offered no details of the type of legislation they would want to see, and President Trump’s spokeswoman offered only a broad outline.

“I have a love for these people (DACA recipients), and hopefully now Congress will be able to help them and do it properly,” President Trump later told reporters at the White House, adding, “I think it’s going to work out very well.”

Since President Trump took office in January, Congress has been unable to pass any major legislation, most notably failing on a health care overhaul, and lawmakers have been bitterly divided over immigration in the past.

“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 Rep. Nancy Pelosi of California, the top Democrat in the House of Representatives.

Virginia’s U.S. senators, Tim Kaine and Mark Warner, criticized the president’s action, saying it would leave young people in limbo.

“President Trump has made a heartless decision to target hundreds of thousands of young people who were brought to the United States through no fault of their own, breaking his promise that these ‘incredible kids’ could ‘rest easy,’ and putting them at risk for being torn away from their families,” said Sen. Kaine, who ran last November for vice president on the Democratic ticket with Mr. Trump’s opponent, Hillary Clinton.

“In Virginia, 12,000 of these Dreamers are neighbors, friends and students who just want the opportunity to contribute to their communities and our economy. Today’s action will force DACA recipients back into the shadows and put them in danger of being deported from the only home they’ve ever known. Congress should immediately pass the bipartisan DREAM Act to protect these kids and then find an agreement on long-overdue, comprehensive immigration reform,” he said.

Virginia’s Democratic attorney general, Mark Herring, announced that the state is part of a coalition of 16 planning to file suit in the coming days to defend Dreamers from the DACA termination.

“There is no upside to ending DACA,” Mr. Herring stated. “Only downside. It will hurt Virginia’s economy and make our communities less safe. It will needlessly tear families apart, burden social services and turn our back on promising, talented young people who want our country to succeed. I’m hopeful that Congress will do the right thing and fix this problem right away. But if they do not, we’ll be ready to defend Virginia Dreamers in court.”

Nearly 800,000 people stepped forward, admitted their illegal immigrant status and provided personal information to the government to apply for the DACA program. They now face the prospect of being deported starting in March. Dreamers are a fraction of the roughly 11 million illegal immigrants in the United States.

“The cancellation of the DACA program is reprehensible,” the U.S. Conference of Catholic Bishops said in a statement.

But White House spokeswoman Sarah Sanders said, “It’s not cold hearted for the president to uphold the law.”

President Trump said DACA recipients would not be deportation priorities unless they are criminals or gang members.

Ending DACA was the latest action by President Trump sure to alienate Latino Americans, a growing segment of the U.S. population and an increasingly important voting bloc. Most of the immigrants protected by DACA came from Mexico and other Latin American countries.

The Mexican government said it “profoundly laments” President Trump’s decision to end DACA and pledged to strengthen efforts to guarantee consular protections for affected Mexican citizens.

The Homeland Security Department will provide a limited window — until Oct. 5 — for some DACA recipients whose work permits expire before March 5 to apply to renew those permits. In addition, the department will adjudicate any new DACA requests, or renewal requests, accepted as of Tuesday. That would mean that some beneficiaries of DACA could work legally in the country through 2019.

House Speaker Paul Ryan, a Republican, called on lawmakers to find a long-term solution for the young people affected by the reversal of the program. Republican Senate Majority Leader Mitch McConnell said Congress “will continue working on securing our border and ensuring a lawful system of immigration that works.”