The White House has revealed its plans for closing the controversial Guantanamo Bay detention facility, one of the president’s long-standing goals.
The Pentagon has proposed transferring the remaining 91 detainees to their home countries or to US military or civilian prisons.
But Congress is deeply opposed and expected to block the move.
The prison costs $445m (£316m) to run annually and closing it was an early promise from President Barack Obama.
He told reporters on Tuesday the prison undermines national security.
“This is about closing a chapter in our history,” said Mr Obama. “It reflects the lessons we’ve learned since 9/11 – lessons that must guide our nation going forward.”
The Pentagon outlined four main components of the plan:
transfer 35 detainees to foreign countries who have been designated to do so
do periodic reviews of remaining detainees to see if their detention is still necessary
continue to use legal tools to deal with remaining detainees
working with Congress to establish a location in the US to hold detainees who will not go to foreign countries
It estimates the move would save up to $180m (£128m) per year in cost savings.
The president, who will complete his second and final term in January, said it was important not to pass the problem on to his successor.
“Keeping this facility open is contrary to our values. It undermines our standing in the world. It is viewed as a stain on our broader record of upholding the highest standards of rule of law.”
Analysis – Tara McKelvey, BBC White House reporter
President Obama has tried for years to close Guantanamo.
He and his deputies say that it hurts the reputation of the US and that militants use “the infamous orange jumpsuit”, as one senior administration official described it, as a recruiting tool.
But members of Congress have baulked at Mr Obama’s plan to close the prison, saying they believe it should remain open – and they don’t want any detainees to be transferred to the US. Representative Mike Pompeo of Kansas, for example, said the prisoners should “stay right where they are”.
Lately, though, White House officials said that lawmakers, or at least some of them, seem more receptive to the idea.
A senior administration official told reporters that there’s “room for conversation”. That’s important since Mr Obama has less than a year to close the prison – and for him time is of the essence.
The plan does not specify where in the US detainees would go.
But the Pentagon has considered 13 different locations in the US, including seven prisons in Colorado, South Carolina and Kansas, and six other places on military bases.