They said he should spend the majority of his life in prison, but their request is far less than the maximum 90 years he could face.
The recommendation came during closing arguments in the sentencing phase of Manning’s trial at Fort Mead, Maryalnd.
Capt Joe Morrow did not say why prosecutors were not seeking the maximum punishment.
“He’s been convicted of serious crimes,” Capt Morrow said. “He betrayed the US and for that betrayal, he deserves to spend the majority of his remaining life in confinement.”
Manning’s defence lawyer will give his closing argument later on Monday. The judge said she will begin deliberating the punishment on Tuesday.
Manning was convicted on 20 counts, including six violations of the Espionage Act and five counts of stealing protected information.
The 25-year-old Manning leaked more than 700,000 documents, including Iraq and Afghanistan battlefield reports and State Department diplomatic cables, while working in early 2010 as an intelligence analyst in Iraq. He also leaked video of a 2007 US Apache helicopter attack in Baghdad that killed at least nine people, including a Reuters news photographer and his driver.
Prosecutors have called Manning an anarchist computer hacker and attention-seeking traitor. The soldier’s supporters have hailed Manning as a whistleblower.
Manning took the stand last week and apologised for hurting his country. He asked for a chance to go to college and become a productive citizen.
Family members and a psychologist testified for the defence, saying the soldier felt extreme mental pressure in the military because of his gender-identity disorder during the era when openly gay people were not allowed to serve.
Capt Morrow said there were other people in Manning’s unit who were openly gay and Manning did not hide his sexuality from them.
“It wasn’t the military’s fault, it wasn’t the command’s fault, it wasn’t because he saw something horrible - it was because he had an agenda,” Capt Morrow said.