Immigrant rights advocates, worker's unions and allied organizations join with immigrant families in Miami last year to protest the Supreme Court's split decision that denied the implementation of President Barack Obama's immigration relief program known as DAPA. (Joe Raedle/Getty Images)

Top Republican officials in 10 states are threatening to take legal action against the Trump administration if it does not end an Obama-era program that has granted deportation reprieves to nearly 800,000 undocumented immigrants who arrived in this country as children.

In a letter sent to U.S. Attorney General Jeff Sessions by Texas Attorney General Ken Paxton, the group of attorneys general — plus Idaho Gov. C.L. “Butch” Otter — gave the administration until Sept. 5 to begin phasing out the 2012 Deferred Action for Childhood Arrivals program, known as DACA, before they take up the issue in federal court.

“This request does not require the Executive Branch to immediately rescind DACA or Expanded DACA permits that have already been issued,” the letter sent Thursday states. “And this request does not require the federal government to remove any alien.”

On Friday, a Justice Department spokesman said the department is reviewing the letter and would not comment.

Homeland Security Secretary John F. Kelly said DACA would remain in place two weeks ago when he rescinded President Barack Obama’s 2014 memo authorizing the Deferred Action for Parents of Americans and Lawful Permanent Residents program. The latter program, which had been blocked in court, had “no credible path forward,” Kelly said.

The officials now demanding the end of DACA were plaintiffs in the federal court case in Texas that successfully stopped the rescinded program, known as DAPA, which sought to shield about 4 million parents of U.S. citizens and green-card holders from deportation.

Groups seeking tougher immigration laws argue that the Trump administration would have an equally tough time defending DACA in court.

‘This program was improper under the Obama administration, and it’s still improper and, in our view, unconstitutional under the Trump administration,” said Jessica M. Vaughan, director of policy for the Center for Immigration Studies. “Congress is the branch of our government that has the authority to decide who gets to stay in this country as a legal immigrant, not the president.”

Advocates for undocumented immigrants argue that the president has the authority to defer immigration enforcement for specific people, which is what DACA does, while granting two-year work permits that can be renewed.

Since President Trump was inaugurated, the program has grown slightly, adding 17,000 recipients during his first three months in office, according to federal data.

Even so, the DACA advocates said, they are worried that Trump — who overall has intensified immigration enforcement and, as a candidate, promised to end the program on his first day in office — now will use the threat of legal action as an excuse to kill it.

“This will potentially force the Trump administration to review its stance on this or have to defend something that they were originally in favor of rescinding themselves,” said Michael Jarecki, who practices law in Chicago and is part of the American Immigration Lawyers Association advocacy committee.

Simon Sandoval-Moshenberg, legal director of the Legal Aid Justice Center’s Immigrant Advocacy Program in Northern Virginia, said that “people were starting to breathe a little easier” after Kelly said the program would not change. “Now this has really pulled the rug out from under everybody.”