Immigration hardliners are calling on Donald Trump to end the program that allows Dreamers – teenagers and adults who were brought to the US illegally as children – to be given relief from the threat of deportation, as the US president appeared poised to announce that the system will be scrapped, but not for another six months.

Attorney general Jeff Sessions is expected to announce on Tuesday a compromise that looks set to please few on either side of the debate, scrapping the Deferred Action for Childhood Arrivals (Daca) system created under the Obama administration in 2012, but delaying the reversal by six months in order to allow Congress to come up with some sort of replacement plan.

On Tuesday morning, Trump posted a tweet suggesting that reports of such a plan might be accurate:

Congress, get ready to do your job - DACA! — Donald J. Trump (@realDonaldTrump) September 5, 2017

Daca allows eligible, law-abiding young people who arrived illegally as children the chance to apply for temporary rights to live, work and study in the US.

Steven King, an ultra-conservative congressman from Iowa who opposes Daca, said the program should be scrapped without delay and argued that a six-month cushion was a way of allowing moderate Republicans to promote a policy of amnesty for Dreamers, which he warned would be damaging for the party.

“Ending Daca now gives [a] chance to restore rule of law. Delaying so R[epublican] leadership can push amnesty is Republican suicide,” he tweeted on Sunday evening.

Some other conservatives strongly opposed to the program for Dreamers continued to call on Trump to end Daca, but reluctantly agreed to go along with the president’s apparent plan – first reported by Politico on Sunday night – to ask Congress to find a solution first.

“Daca is unconstitutional and I support the ending of it,” Mark Burns, an evangelical pastor from South Carolina and a member of Trump’s evangelical advisory panel, told the Guardian. “We need to eliminate it so it stops immediately.”

He added: “It’s not wrong for an American president to promote the American citizen first. People should come through the door the right way.” He accused illegal immigrants of “crushing” lower-class and middle-class American jobs and said that the Daca provisions for so-called Dreamers had created an unfair loophole in the law.

“I believe giving Congress six months to come up with a solution can work; I don’t think the president wishes just to uproot people,” he said.

Trump pledged during the election campaign that he was going to rip up Daca immediately if he won the White House.

Donald Trump has faced criticism for failing to repeal the Daca program immediately. Photograph: Evan Vucci/AP

“If President Trump had done what candidate Trump promised to do, which was end Daca on day one, there would not be this humming and hawing that we’ve seen from him and all this awful speculation,” said Joe Guzzardi, a spokesman for Californians for Population Stabilization, which opposes giving legal status to Dreamers.

“Millions of people voted for him on the basis of that promise and the delay has been a huge disappointment,” he said.

Guzzardi said he gave Congress “zero chance” of coming up with a viable replacement for the Daca scheme in six months. Meanwhile, those on Daca work permits should be told they will not be renewed and then Dreamers should have to go through new, tougher background checks, he said.

“If they have a record of, for example, two misdemeanor crimes or identity theft, they should be dealt with harshly. A lot of these Dreamers held jobs before Daca so they either used stolen or falsified identity documents and that’s a crime,” he said.

However, progressive leaders are equally horrified by the prospect of Trump failing to protect Dreamers and jeopardizing their legal status after the Daca program had led them to believe they could safely declare themselves to the government.

New York governor Andrew Cuomo and his state attorney general Eric Schneiderman on Monday pledged to sue the Trump administration if it scraps the Daca program, saying it “would be cruel, gratuitous, and devastating to tens of thousands of New Yorkers”.

Schneiderman said Dreamers paid taxes, played by the rules, and were “Americans in every way”.

“I will sue to protect them,” he said. “They’ve earned the right to stay in the only home they have ever known.”

Cuomo said: “We cannot sit on the sidelines and watch the lives of these young people ruined.”

A rally in New York City against the repeal of Daca. Photograph: Albin LJ/Pacific/Barcroft Images

Bob Ferguson, the attorney general of Washington state, also threatened to sue Trump if he ended Daca, and warned that others likely to follow suit.

“We have been working closely with legal teams around the country, and we expect to be joined by other states in this action,” he said in a statement.

Bernie Sanders, the independent senator from Vermont and past presidential hopeful in the 2016 campaign, tweeted: “If Trump decides to end Daca, it will be one of the ugliest and cruelest decisions ever made by a president in our modern history.”

Obama initiated the Daca policy because Congress repeatedly failed to pass comprehensive immigration reform, especially the so-called Dream Act, which gave Dreamers their nickname and would have given those deemed eligible permanent legal residency status.

Steven Choi, executive director of the New York immigration coalition, which advocates for refugees and immigrants, said Trump’s apparent decision to attempt a compromise over Daca was “incredibly cynical”.

“He’s trying to avoid accountability,” he told the Guardian. “I have no faith in Congress’s ability to come to some sort of agreement on this – it’s a joke.”

Choi added that a move to end Daca would “defile the American presidency, already marred by Trump’s overt sympathies for white supremacists”, a reference to the president’s statements after the violent neo-Nazi march in Charlottesville, Virginia, last month and his decision to pardon former Arizona sheriff Joe Arpaio, who was infamous for aggressive racial profiling in in his law enforcement methods.

“Trump is trying to appeal to the lowest part of his base and it’s a tragedy,” said Choi.