United States President Barack Obama is expected to sign a draft executive order on Thursday saying the Guantanamo Bay detention centre should be shut down within a year.
The draft also proposes that the US Attorney-General review cases to decide whether detainees are released, transferred to their own countries or tried in American civil courts.
Mr Obama made it clear throughout his presidential campaign that the US military prison in Cuba would go.
The draft order circulated on Wednesday also called for halting military trials in the prison, where terror suspects had been held for years without trial.
Separate orders are expected to ban abusive interrogations and review the detention of terror suspects.
Military judges have already agreed to suspend the trial of five men accused of plotting the terror attacks of September 11, 2001.
There are 250 men being held at the Guantanamo Bay detention centre; their eventual fate is still unknown.