A spokesman says South Sudan's president will seek election next year, in what will be the first vote on Salva Kiir's leadership since the turbulent country won independence.
Ateny Wek Ateny told The Associated Press that Kiir "is a uniting factor. If he leaves power now, the whole country will collapse."
Kiir was elected in 2010, a year before the country gained independence from Sudan. Elections set for 2015 were delayed by civil war.
The United Nations has warned that South Sudan is at risk of genocide.
The international community has grown frustrated with Kiir and other South Sudan leaders. In his last remarks as U.S. special envoy before leaving office in January, Donald Booth said the United States "wanted peace for South Sudan far more than its leaders did."