The next day the Supreme Military Council withdrew its support from Bakhtiyar, and on February 12, 1979, following sporadic street gunfight, all organs of the regime (political, administrative, and military) finally collapsed. The revolution had triumphed. On March 30 and 31, a nationwide referendum resulted in a massive vote in favor of the establishment of an Islamic Republic. The only question on the ballot was "Islamic Republic: Yes or No-. .
Ayatollah Khomeini proclaimed the next day, April 1, 1979, as the " first day of God's government". He obtained the title of "Imam," which is the highest religious rank in Shia. With the establishment of Islamic Republic of Iran he became Supreme Leader (Vali-e Faqeeh). .
The new prime minister, Mehdi Bazargan, had significant problems to deal with. He headed a government that controlled neither the country nor even its own bureaucratic apparatus. Central authority had broken down. Hundreds of semi-independent revolutionary committees, not answerable to central authority, were performing a variety of functions in major cities and towns across the country. Factory workers, civil servants, white-collar employees, and students were often in control, demanding a say in running their organizations and choosing their chiefs. The lower ranks or local inhabitants frequently rejected governors, military commanders, and other officials appointed by the prime minister. .
As the supreme leader, Ayatollah Khomeini did not consider himself bound by the government. He made policy pronouncements, named personal representatives to key government organizations, established new institutions, and announced decisions without consulting his prime minister. Bazargan found he had to share power with the Revolutionary Council, which Ayatollah Khomeini had established in January 1979 and which initially was composed of clerics close to Ayatollah Khomeini, secular political leaders identified with Bazargan, and two representatives of the armed forces.