Fighting erupted in South Sudan last month when President Salva Kiir accused former Vice President Riek Machar of trying to overthrow the government. Both men are from rival ethnic communities. Machar was sidelined when Kiir reshuffled his Cabinet in July and denies attempting a coup.
Tigist Hailu, a spokeswoman for the eight-member Intergovernmental Authority on Development, used her official Twitter account to announce a cease-fire deal was expected from multilateral discussions under way in Ethiopia.
"South Sudanese parties [will] sign today in Addis [Ababa] cessation of [hostilities] and [question] of detainees [agreements]," her message read.
The United Nations estimates more than 500,000 people have been displaced by fighting, which according to the International Crisis Group has left as many as 10,000 people dead since fighting began.
U.S. State Department spokeswoman Marie Harf said during her regular press conference Wednesday representatives from both sides needed to sign agreements in Ethiopia "because fighting on the ground needs to stop."
Washington helped broker a 2005 peace agreement ending Sudan's civil war and paving the way to South Sudan's independence in 2011.