WASHINGTON President Donald Trump threatened in mid-October to pull out of the Iran nuclear deal unless Congress passed legislation that changed the terms of the 2015 agreement negotiated between Iran, the U.S. and five world powers. But more than a month later, a Republican-led effort to meet his demand has stalled after failing to attract bipartisan support.

Congress is an independent branch of government, Sen. Ben Cardin (D-Md.), ranking member of the Foreign Relations committee, told reporters on Wednesday. We dont take orders from the president; we take orders from our constituents.

The same day Trump threatened to pull out of the deal, Senate Foreign Relations Committee Chairman Bob Corker (R-Tenn.) and Sen. Tom Cotton (R-Ark.) began drafting legislation to satisfy the presidents request. Under the agreement, Iran is committed to never developing a nuclear weapon, but some of the restrictions on its nuclear program expire or sunset after 10 to 15 years. Corker and Cottons plan was to tweak existing oversight legislation so that the U.S. would no longer honor these sunset clauses and would automatically reimpose nuclear sanctions against Iran if its nuclear program reached a point in which it could acquire a nuclear weapon in less than a year.

Secretary of State Rex Tillerson pressed lawmakers to pass Corker and Cottons legislation before Trump faces another Iran deal certification deadline in January. Corker told reporters a month ago that he hoped to introduce the text of the bill within the following two weeks.

But Corker and Cotton appear to have made little progress in the past month. They have not released text of the legislation or announced any Democratic partners. Cardin acknowledged discussions about what the president would like to see from Congress but said he is not aware of there being any Corker-Cotton bill.

Corker, who is retiring when his term ends, has feuded publicly with Trump and expressed concern that the president could set off World War III.

When Corker previewed his proposed legislation last month, he argued that it in no way violates the Iran nuclear deal and said he was committed to working across party lines. But Democrats and nuclear nonproliferation groups said that the legislation amounted to a unilateral move to back out of the U.S. commitments under the international agreement.

Corker has now admitted that he has shelved it, because it was a non-starter, a top Senate aide told The Jerusalem Post last week.

Micah Johnson, a spokeswoman for Corker, slammed The Jerusalem Post story as based solely on bogus anonymous sources who clearly are not involved in our discussions.

Asked about the current state of the Corker-Cotton legislative effort, Johnson was vague. Sen. Corker continues to talk with Sen. Cardin, Sen. Cotton and the administration about the appropriate path forward, she said.

Caroline Tabler, a spokeswoman for Cotton, said that although no bill has been introduced, Cotton, Corker, Cardin and the Trump administration are working on legislation that reflects the Cotton-Corker framework they released last month.

Though Democrats and the U.S.s European allies, who oppose altering the deal, have so far been successful in warding off legislation that would violate the agreement, they cant block Trump from blowing up the agreement himself.

In the event we are not able to reach a solution working with Congress and our allies, then the agreement will be terminated, Trump vowed last month.

For now, the plan from proponents of the Iran deal appears to be hoping that Trump will fail to follow through on yet another promise .