Iran has officially dropped a key "red line" demand that had been a major sticking point in efforts to revive the Iran nuclear deal, a senior administration official told CNN, the latter reported.

In its response to a draft nuclear deal agreement proposed by the European Union—which the EU has described as a "final" draft—Iran did not demand that the Islamic Revolutionary Guard Corps (IRGC) be removed from the US State Department's list of Foreign Terrorist Organizations, the official said.

"The current version of the text, and what they are demanding, drops it," the official said, noting that the US had repeatedly and consistently rejected the demand. "So if we are closer to a deal, that's why."

The Iranians also dropped demands related to delisting several companies tied to the IRGC, the official said.

The official added that "the President has been firm and consistent that he will not lift the terrorism designation of Iran's Revolutionary Guards Corps." But the official said that while a deal is now "closer than it was two weeks ago, the outcome remains uncertain as some gaps remain. President Biden will only approve a deal that meets our national security interests."

Progress from this point forward could be slow, another senior administration official said. But there does seem to be more momentum now than there has been in the past year.

US President Joe Biden has insisted for months that he would not lift the IRGC terrorist designation in order to revive the nuclear deal, known as the Joint Comprehensive Plan of Action.