WASHINGTON — (CNN) The White House on Wednesday refused to rule out executive action to close the military prison at Guantanamo Bay, saying past refusal from Congress to take steps to shutter the facility have led to little optimism that a legislative solution is possible.

White House Press Secretary Josh Earnest, asked about the possibility that President Barack Obama could take unilateral moves to transfer detainees to the United States, said all options remain in play.

“At this point, I would not take anything off the table in terms of the President doing everything that he can to achieve this critically important national security objective,” Earnest said.

The White House is finalizing a Guantanamo closure plan that’s expected to be delivered to Congress in the coming days. The plan will recommend speeding detainee transfers to other nations, and allowing for some prisoners to be relocated to facilities in the United States.

Defense officials have been surveying sites in South Carolina, Kansas and Colorado as potential locations to house Guantanamo detainees who the U.S. government has determined cannot be transferred to their home countries.

That would require Congress to change a law banning any Guantanamo transfers to the U.S. Opponents of moving detainees to the United States cite the potential security concerns of keeping accused terrorists on U.S. soil.

On Wednesday, Earnest said there was little confidence Congress would give the administration’s upcoming proposal due consideration.

“There is an open question about whether or not Congress does want to fairly consider this proposal,” he said. “I guess we’ll find out.”

Obama vowed during his first campaign for president he would close the Guantanamo Bay prison, saying it serves as a recruiting tool for terrorists. And as more individuals are transferred out, the cost-per-detainee has increased to millions of dollars per year.

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