WASHINGTON (AFP) - Pressure mounted on President Donald Trump not to end an amnesty for people brought to the United States illegally as children, with Republican allies and the chief executives of major US firms from Amazon to General Motors urging compassion on Friday (Sept 1).

In a letter to the White House and top Republicans and Democrats in Congress, business leaders - including executives at Cisco, eBay, Facebook, Marriott and Microsoft - warned of the moral and economic impact of forcing almost 800,000 people back into the legal shadows.

Meanwhile, top Congressional Republican Paul Ryan and a slew of his party's lawmakers pressed Trump to step back from a campaign pledge to axe the programme.

"I don't think he should do that. I believe this is something Congress has to fix," Ryan told local radio station WCLO. "These are kids who know no other country, who were brought here by their parents and don't know another home. And so I really do believe there needs to be a legislative solution."

Trump indicated he had not yet decided whether to end the programme instituted by former president Barack Obama, which allowed children brought to the country illegally before they were 16 to get a two-year renewable work permit.

The White House said Trump would make his announcement on the policy on Tuesday.

The programme known as DACA, or Deferred Action for Childhood Arrivals, was instituted by then president Barack Obama in 2012 via executive order and could be repealed by Trump with the stroke of a pen.

Recipients of the programme "grew up in America, registered with our government, submitted to extensive background checks and are diligently giving back to our communities and paying income taxes," the chief executives argued in the letter.

These "hardworking young people will lose their ability to work legally in this country, and every one of them will be at immediate risk of deportation. Our economy would lose US$460.3 billion (S$624.5 billion) from the national GDP and US$24.6 billion in Social Security and Medicare tax contributions."

Trump had vowed to end the programme and is under fierce pressure by anti-immigrant supporters to make good on that promise.

On Thursday, Fox News reported that Trump would stop issuing DACA permits and allow the existing ones to expire.

FEAR OF DEPORTATION

DACA recipients fear their legal status could lapse and authorities would be able to locate them easily for deportation.

The policy has become tied up in a debate about congressional funding for Trump's proposed wall on the border with Mexico.

Some in Congress have suggested a deal could be reached for the permit system to remain in place if lawmakers agree to release funding for the wall, or as part of broader immigration reform.

Some White House officials said Trump's decision would have to wait until after mega-storm Harvey subsides.

Hurricane-hit Texas alone has issued over 200,000 permits or renewals under the DACA scheme, according to the Department of Homeland Security.