President Kiir signed an amended law on Monday that also dissolved national and state governments. He will remain in office with full constitutional powers until an elected president is sworn in after the 22 December elections. Some ministers and governors have been reappointed in caretaker positions.
The country has postponed elections twice before and extended the transitional period several times. Kiir is the presidential candidate of his Sudan People's Liberation Movement (SPLM), and no prominent figures have announced plans to challenge him. The main opposition leader, Riek Machar, was sacked as vice-president last year and charged with treason; he remains under house arrest. Machar had been named vice-president as part of a 2018 peace deal that ended a five-year civil war between forces loyal to the two men.
Ahead of Tuesday's announcement, soldiers from the army and national security services blocked access to government ministries in Juba and patrolled parts of the city. A senior government official told the BBC that staff arriving for work were turned away and told to return the following Monday. UN agencies in Juba asked staff to work remotely while the situation was monitored.
The dissolution clears hurdles to the long-delayed election but raises concern that Kiir can now wield unchecked power, according to observers.