On 6 July 2004, in an open letter, Sihanouk announced his plans to abdicate once again. At the same time, he criticised Hun Sen and Ranariddh for ignoring his suggestions on how to resolve the political stalemate of the past year. Meanwhile, Hun Sen and Ranariddh had agreed to introduce a constitutional amendment that provided for an open voting system, requiring parliamentarians to select cabinet ministers and the president of the National Assembly by a show of hands. Sihanouk disapproved of the open voting system, calling upon Senate President Chea Sim not to sign the amendment. When Chea Sim heeded Sihanouk's advice, he was ferried out of the country shortly before the National Assembly convened to vote on the amendment on 15 July. On 17 July 2004, the CPP and FUNCINPEC agreed to form a coalition government, leaving SRP out as an opposition party. On 6 October 2004, Sihanouk wrote a letter calling for the throne council to convene and select a successor. The National Assembly and Senate both held emergency meetings to pass laws allowing for the abdication of the monarch. On 14 October 2004, the throne council unanimously voted to select Norodom Sihamoni as Sihanouk's successor. Sihamoni was crowned as the King of Cambodia on 29 October 2004.