The U.S. military is preparing a bulk transfer of 10 detainees on Thursday from its detention center at Guantanamo Bay, Cuba, two defense officials told Fox News.

The transfer, amounting to about 10 percent of the remaining prisoners, marks the largest group of detainees to be shipped out of the camp since Defense Secretary Ash Carter informed Congress in December his department would transfer a wave of detainees at the beginning of 2016.

The accelerated transfers reflect a renewed effort by the president – who is likely to highlight the issue in the State of the Union address Tuesday night – to shutter the controversial prison camp. But the moves have heightened security concerns, as some of the latest detainees being shipped out were deemed medium- or high-risk prisoners.

“All these guys are the ‘hardcore’ type; if not, they would have been transferred earlier,” said one official familiar with the list of those being transferred Thursday.

The upcoming transfer would bring the number of detainees moved out of the camp this year to 14; the administration is looking to transfer a total of 17 in the coming weeks. Right, now, there are 103 detainees remaining at the camp, and all have ties to Al Qaeda or other terrorist groups.

A Pentagon spokesman would not comment on the bulk transfer Thursday when reached by Fox News.

The 10 detainees are expected to go to countries in the Middle East, but officials declined to outline which ones specifically.

The transfers are part of an administration effort to bring down the prison camp’s population as much as possible. Fifty-nine prisoners, however, currently are not eligible for transfer abroad, and the administration is trying to figure out what to do with them.

Though Congress has blocked transfers to the United States, the Pentagon nevertheless has conducted a series of site surveys of prisons in the U.S. in the past few months. 

Federal prisons in Colorado, Kansas and South Carolina were assessed by defense officials. The Pentagon was supposed to deliver a report to Congress with its findings and recommendations, but that report has not yet been delivered and is currently stalled, according to officials familiar with the matter.

White House Chief of Staff Denis McDonough, on “Fox News Sunday,” vowed that President Obama will close the Guantanamo Bay detainee facility before his presidency ends. McDonough sidestepped the question of whether the president would use his executive powers to close the facility, if Congress continues to resist.

The Pentagon announced the most recent transfer, Muhammed Abd Al Rahman Awn Al-Shamrani, on Monday – the fourth so far this year. Al-Shamrani had been held in Cuba for 14 years and, according to his leaked prisoner file, was suspected of Al Qaeda ties. He was deemed a “high threat” to the United States, according to a U.S. military memo recommending continued detention in 2008. If released without “close supervision,” the memo warned, Shamrani will “immediately seek out prior [Al Qaeda] associates and reengage in hostilities.”

He was transferred to his home country of Saudi Arabia.

It is estimated that 30 percent of detainees transferred out of the prison re-engage or are suspected of re-engaging in hostile activities, according to the Department of Defense.

Sens. Kelly Ayotte, R-N.H., and Lindsey Graham, R-S.C., sent a letter to the leaders of the Senate Armed Services Committee Monday requesting a hearing as soon as possible regarding the Obama administration's transfers of terrorist detainees from Guantanamo.

White House Press Secretary Josh Earnest, asked about the president’s Guantanamo plans Tuesday morning on Fox News, reiterated the goal of closing the camp before Obama leaves office.

“That is what we intend to do,” he said.

Lucas Tomlinson is the Pentagon and State Department producer for Fox News Channel. You can follow him on Twitter: @LucasFoxNews