Once in office, Sihanouk introduced several constitutional changes, including extending suffrage to women, adopting Khmer as the sole official language of the country and making Cambodia a constitutional monarchy by vesting policy-making powers in the prime minister rather than the king. He viewed socialism as an ideal concept for establishing social equality and fostering national cohesion within newly independent Cambodia. In March 1956, he embarked on a national programme of "Buddhist socialism", promoting socialist principles on the one hand while maintaining the kingdom's Buddhist culture on the other. Between 1955 and 1960, Sihanouk resigned and retook the post of prime minister several times, citing fatigue caused by overwork. The National Assembly nominated experienced politicians such as Sim Var and San Yun to become prime minister whenever Sihanouk took leave, but they similarly relinquished their posts each time, several months into their term, as cabinet ministers repeatedly disagreed over public policy matters.