Just two witnesses remain on the government's schedule for Friday's session at Fort Meade, near Baltimore.
Manning faces up to 90 years in prison for disclosing reams of classified information through the anti-secrecy website WikiLeaks. He claims he leaked the material to expose wrongdoing and provoke discussion about U.S. military and public affairs.
Prosecutors have presented evidence that the leaks put some foreign citizens at risk of harm and hampered U.S. foreign relations. Several ambassadors were recalled or expelled. And there was a pullback in interagency sharing of classified information.
The defence case beginning Monday will focus on assertions by Manning and his lawyers that he was a naive, but well-intentioned soldier.