A potential lawsuit from Republican state attorneys general might force the Trump administration to enact a campaign trail promise.

Texas Attorney General Ken Paxton and Republican attorneys general in nine other states sent a letter to U.S. Attorney General Jeff Sessions that said that they will sue the federal government if it does not begin to phase out the Deferred Action for Childhood Arrivals program.

The DACA program, which was started by former President Obama, protects around 790,000 illegal immigrants who arrived in the U.S. as minors. Secretary of Homeland Security John Kelly told members of the Congressional Hispanic Caucus Wednesday that he can’t assure them that the administration would prevail over this legal challenge.

DHS spokesman David Lapan told The Washington Post, “This is what he’s being told by different attorneys, that if it goes to court it might not survive.”

President Trump said on the campaign trail that he would “immediately terminate” the DACA program that was started through an executive order. He has reneged on this promise and an estimated 98,000 illegal immigrants have received protection from deportation and work permits during the first few months of Trump’s tenure in office.

However, with this lawsuit looming Trump’s promise seems poised to be implemented.

“Jeff Sessions is going to say, ‘Deport them,'” Democratic Illinois Rep. Luis Gutierrez told the Post. “If you’re going to count on Jeff Sessions to save DACA, then DACA is ended.”