WASHINGTON — (CNN) President Barack Obama, in his final month in office, is moving to leave as few prisoners in Guantanamo Bay as possible, notifying Congress that the administration intends to transfer out some of the detainees before Donald Trump is sworn in.

The Gitmo downsizing move could rankle Trump, who pledged during the campaign to keep the prison open and “load it up.”

A congressional official told CNN that they received notice Monday of the White House’s intention to transfer some additional detainees. And, another congressional source said, Congress has been informed that the White House will make notifications of more transfers within the next 24 hours.

The notification comes on the last day possible, as the administration is legally required to provide Congress with 30 days notice prior to transferring any of the on facility’s detainees.

Of the 59 prisoners remaining at Guantanamo, 22 are currently eligible for transfer, according to the Pentagon. Congressional officials would not say exactly how many the administration is seeking to transfer, although one official said it would be fewer than the 22 who are eligible.

The New York Times, which first reported the story, quoted officials saying the number was either 17 or 18.

According to information provided by the Defense Department, 10 additional detainees are involved in criminal proceedings, with the remaining 27 currently eligible for appearances before the Periodic Review Board. The panel is comprised of national security officials who determine whether the remaining detainees represent a threat to the US.

Obama came into office pledging to shutter Guantanamo but his efforts were largely rebuffed by a Republican-led Congress that passed legislation barring the Defense Department from transferring inmates to US soil.

“The politics of fear has led Congress to prevent any detainees from being transferred to prisons in the United States,” Obama told US troops at MacDill Air Force Base, the headquarters of Central Command, earlier this month. “Until Congress changes course, it will be judged harshly by history, and I will continue to do all that I can to remove this blot on our national honor.”

Despite the resistance, the administration has whittled down the population there significantly from the 242 detainees it inherited in January 2009.

Recent months have seen a major uptick in relocations, with the largest detainee transfer under Obama taking place in August,

Many of the remaining detainees are thought to come from countries like Yemen, which are considered too unstable to adequately receive and monitor former prisoners, making the agreement of third-party countries like the UAE essential to completing the relocations.

While it is clear that Obama will not be able to live-up to his initial pledge to close the detention facility, as he plans to hand off power to Trump on January 20 it appears that his team is striving to leave as few inmates as possible.

Trump has pledged to keep the Guantanamo open, telling a crowd in February in Nevada: “We’re gonna load it up with some bad dudes.”

The White House declined to comment on issues relating to pending transfers.

The Office of the Director of National Intelligence, which tracks recidivism among former inmates, said in a September report that nine of 161 inmates released since January 2009 had returned to supporting terrorist groups. An additional 11 are “suspected” of having gone back to terrorist activity, though the report notes that the Defense Intelligence Agency puts that number at 15.

During the George W. Bush administration, 113 of 532 released prisoners were confirmed to have reengaged in terrorism, the report said.