At the heart of the threat is ongoing litigation in another related program -- giving the attorneys general an opening to squeeze the administration on DACA.
Despite explicitly pledging during the campaign to "immediately" rescind DACA, the Trump administration has continued to honor the program and issue new permits under it.
The administration has largely tried to have it both ways, continuing the program and pledging to protect its recipients while at the same time saying that situation is not necessarily permanent and arresting individuals that officials say have lost their DACA status. The position has angered activists on both sides of the issue, who have expressed rare agreement on the frustration that the administration won't clearly articulate its long-term plans for DACA.
At issue is pending litigation in Texas that has challenged an Obama administration extension of DACA, a program that allows undocumented immigrants brought to the US as children protection from deportation and the ability to work and study, and a similar program instituted for parents of childhood arrivals, which was never allowed to go into effect by the courts.
But Paxton wrote that if the administration doesn't end DACA by September 5, Texas will amend its complaint in the case to include DACA -- which would force the administration to defend the program in litigation or abandon it.
"We respectfully request that the Secretary of Homeland Security phase out the DACA program," Paxton wrote in the ultimatum. "Otherwise, the complaint in that case will be amended to challenge both the DACA program and the remaining Expanded DACA permits."
The Department of Justice and DHS did not respond to a request for comment on the letter. Sessions was asked about it on "Fox and Friends" on Friday, and seemingly praised the states.
"The DAPA law has already been withdrawn," Sessions said when asked what changes could be coming. "That was a big victory, and we'll be looking at that. But I've got to tell you, I like it that our states and localities are holding the federal government to account, expecting us to do what is our responsibility to the state and locals, and that's to enforce the law."
Despite railing against DACA during the campaign, Trump showed a more sympathetic side side after his election.
"We're going to show great heart," Trump said in a news conference in February. "DACA is a very, very difficult subject for me, I will tell you."
But he also spoke of possible abuses of the program.
"To me, it's one of the most difficult subjects I have because you have these incredible kids, in many cases, not in all cases. And some of the cases, having DACA and they're gang members and they're drug dealers, too. But you have some absolutely incredible kids, I would say mostly."
Immigration advocates, on the other hand, decried the move by the states and called on Congress and the administration to commit to DACA.
"Everyone who has seen DACA ... should really be appalled by this legal low blow on the part of Texas. It's nothing sort of shameful, it's nothing short of repugnant," said Kamal Essaheb, director of policy and advocacy at the National Immigration Law Center, on a call with reporters Friday.
Essaheb also blamed Trump for the whole episode, saying he protected DACA while going after its recipients' communities.
"These mixed messages have caused the situation that even allows Texas to consider what it did," Essaheb said. "The Trump administration can and should shut this down."
Congress has a handful of bipartisan proposals introduced to make DACA permanent by law, thus nullifying the court challenge, but none have received a vote.
Thursday's letter was signed by Paxton and the attorneys general of Alabama, Arkansas, Idaho,