The revolution was a big tent group that included Islamists, a spectrum of leftists, and people who wanted a system more similar to what was proposed in the Revolution of 1906. The term Islamic Republic was vague enough to appeal to a lot of different people. The US letting the deposed Shah into the country for medical treatment and the ensuing hostage crisis hardened anti-Western views and gave legitimacy to the theocrats. The clerical establishment were able to maneuver their way into more and more power from 1979 until the end of the 80s through a variety of tactics.