sentences:  They formed a coalition with the Progressive Party and Independence Party leader Geir Hallgrímsson was elected Prime Minister.Following the 1971 elections, a coalition government had been formed by the Progressive Part, People's Alliance and Union of Liberals and Leftists with the Progressives' Ólafur Jóhannesson as Prime Minister.Early elections were triggered by the collapse of the coalition due to a petition to reconsider a policy that would close the United States naval base in Keflavik.