With less than a year left in his final term, US President Barack Obama has presented a last-ditch plan to close the Guantanamo Bay detention facility, a move staunchly opposed by the Republican-controlled Congress and the three leading Republican presidential candidates.

There are currently 91 detainees left in Guantanamo, 35 of whom have already been cleared for release. During the height of detentions under the Bush administration, 800 people were held at the facility.

Under the president's plan, review boards would determine which detainees among the remaining 56 are eligible for release to other countries. Those who aren't cleared would be held at a facility in the continental United States.

"Keeping this facility open is contrary to our values," President Obama said on Tuesday. "It undermines our standing in the world; it is viewed as a stain in our broader record of upholding the highest standards of the rule of law."

But it remains to be seen whether or not the administration's plan will actually uphold those high standards, according to Omar Shakir with the Center for Constitutional Rights (CCR).

"This administration, even in its plan, seems to suggest that there is an irreducible number that will in fact need to be detained in the United States," Shakir told DW.

"For whatever reason, the United States has determined it cannot charge them," Shakir said, "either because there's no evidence to implicate them in a crime or because any evidence is tainted by torture."

'One-way ticket to Guantanamo'

Before detainees can be transferred to the United States, the White House has to find a facility where they can be held. Thirteen potential sites have been identified by the Pentagon. Congress, however, has placed restrictions on the president.

"In order to close Guantanamo, this plan will require congressional support and legislation," Matthew Waxman, a former deputy assistant secretary of defense for detainee affairs, told DW.

"Currently there are legislative restrictions on bringing detainees into the United States, for example, and the Obama administration would need to work with Congress to lift those," Waxman said.

But convincing Congress will prove difficult. Even when there were Democratic majorities in 2010, Congress refused funding to transfer Guantanamo detainees to the United States.

Today, Republicans control the House of Representatives and the Senate. It's a presidential election year, and all three leading Republican candidates - Donald Trump, Ted Cruz and Marco Rubio – are opposed to closing Guantanamo.

"If we capture terrorists alive, they will get a one-way ticket to Guantanamo Bay, and we will find out everything they know," Rubio said in a press release on Tuesday.

"Enemy combatants suitable for trial will be tried in military tribunals," the Florida senator said. "And no Guantanamo detainees will be brought to the United States for trial in our courts."

Fifty-three percent of Americans oppose closing Guantanamo, while just 29 percent of the public are in favor, according to a Rasmussen poll from last year.

'Changing Guantanamo's zip code'

Though the politics are challenging, the administration can take action without Congress, according to Shakir from the CCR. The president has the power to reduce the number of Guantanamo detainees by accelerating their transfer to other countries.

"Almost every step outlined in this plan are ones the president should have taken many years ago and can still take today," Shakir said.

Although the president does need congressional support to transfer detainees to the United States, setting up a new facility wouldn't address the core problem of Guantanamo, Shakir said.

"The infamy of Guantanamo was never in the physical location, but in entrenching a system of indefinite detention without charge," Shakir said. "Transferring men to the US simply changes Guantanamo's zip code."