Hun Sen has been the prime minister of Cambodia for 28 years. He is the leader of the Cambodian People's Party (CPP). In 2013 he was challenged by Sam Rainsy leader of the Cambodia National Rescue Party (CNRP). On 28 July 2013 general elections were held in Cambodia. The ruling Cambodian People's Party claimed victory by winning 68 seats in Parliament. The Cambodia National Rescue Party won 55 seats. They then rejected the election results and boycotted the opening of parliament. The CNRP claimed there had been irregularities with the voting. The European Union (E.U.) and the United States also expressed concern about possible fraud. The international non-governmental organisation Human Rights Watch called for an 'independent commission' to investigate charges of election fraud.