Suramarit, Sihanouk's father, died on 3 April 1960 after several months of poor health that Sihanouk blamed upon the shock that his father had received from the parcel bomb attack. The following day, the Cambodian Crown Council met to choose Monireth as regent. Over the next two months, Sihanouk introduced constitutional amendments to create the new post of Head of State of Cambodia, which provided ceremonial powers equivalent to that of the king. A referendum held on 5 June 1960 approved Sihanouk's proposals, and Sihanouk was formally appointed Head of State on 14 June 1960. As the head of state, Sihanouk took over various ceremonial responsibilities of the king, such as holding public audiences and leading the Royal Ploughing Ceremony. At the same time, he continued to play an active role in politics as Sangkum's leader.