Presidential Chief of Staff Im Jong-seok urged the National Assembly to swiftly come up with a constitutional revision bill. 

During a briefing to the parliament's House Steering Committee on Wednesday, Im said both the ruling and opposition parties had promised during the presidential election to hold a referendum on the matter at the same time as the local elections in June. 

He said the top office hasn't yet decided whether it will wait for the National Assembly or if the president will propose an amendment himself, but will make the necessary preparations.