WASHINGTON (Reuters) – U.S. President Donald Trump is expected to rescind an Obama-era policy that protects nearly 600,000 immigrants who entered the country illegally as children, but plans to let them stay until their work permits expire, a senior administration official said on Thursday.

Trump’s decision could be announced as early as Friday but could also come next week, said the official, who added that the president could always change his mind.

Trump, a Republican, had pledged on the election campaign trail to scrap all of Democratic former President Barack Obama’s executive orders on immigration, including the Deferred Action for Childhood Arrivals, or “Dreamers,” program.

What to do about the so-called Dreamers has been actively debated within the White House and Trump administration. One senior administration official described the debate as a “tug of war” between factions in favor of the move and those opposed.

Officials, believing the DACA program to be ultimately unconstitutional, want Congress to impose a legislative fix for the Dreamers, two officials said.

White House spokeswoman Sarah Sanders told reporters that Trump and his senior advisers were still reviewing the DACA program and that the president not made a final decision on how to proceed.

Asked whether Trump still stood by a comment in February about treating Dreamers “with heart,” Sanders said: “Absolutely, the president stands by his statement. Right now this is currently under review … from a legal standpoint primarily and until that review is complete … we don’t have anything to add further on that front.”

U.S. Representative Steny Hoyer of Maryland, the No. 2 Democrat in the House of Representatives, released a statement expressing concern about reports that Trump may terminate the program, saying this would be “devastating” to many Dreamers.

“In the absence of Congress enacting bipartisan immigration reform, which must remain our goal, the President ought to continue providing peace of mind to DREAMers that they need not live in fear of being sent away from the only home many of them have ever known,” Hoyer said.

Ten Republican state attorneys general in June urged the Trump administration to rescind the DACA program, while noting that the government did not have to revoke permits that had already been issued.

If the federal government did not withdraw DACA by Sept. 5, the attorneys general said they would file a legal challenge to the program in a Texas federal court.

The effort was led by Texas and joined by state attorneys general in Alabama, Arkansas, Idaho, Kansas, Louisiana, Nebraska, South Carolina, Tennessee and West Virginia.

Kayleigh Lovvorn, a spokeswoman for Texas attorney general, on Thursday said her office has no plans to push back the Sept. 5 date.

The overwhelming majority of the Dreamer immigrants came from Mexico and other Latin American countries. Over 200,000 of them live in California, while Texas has over 100,000. New York, Illinois and Florida also have large numbers of DACA recipients.

A larger coalition of 26 Republican attorneys general had challenged the Obama-era policy covering illegal immigrant parents, known as DAPA, that had been blocked by the courts before it took effect. The Department of Homeland Security rescinded that policy earlier this year.

Immigrants who entered the country illegally as children have been able to qualify for DACA if they were under the age of 31 when the program began on June 15, 2012. They would have to have entered the United States before they turned 16, however, and to have lived continuously in the country since June 15, 2007.