Mohammad Reza Pahlavi took power in Iran as Shah in 1941, promising a constitutional monarchy but increasingly consolidated power. He was criticized for being undemocratic and unresponsive to public opinion, as well as aligning too closely with Western powers. In the 1970s, Islamic cleric Ayatollah Khomeini built popular discontent with the Shah's Western-leaning rule and lack of democracy, calling for his overthrow. Mass protests in 1978-1979 led to the collapse of the Shah's government and his exile, replacing it with an Islamic theocracy led by Ayatollah Khomeini.