When the monarchy was overthrown, parliament was replaced with a transitional assembly of 60 select members from government institutions and provinces from 1974 to 1975, after which the government largely operated by decree through the military junta headed by Mengistu Haile Mariam. The period without some semblance of a legislature ended in 1987, when the National Shengo was promulgated under a new constitution drafted by Mengistu and the Workers' Party of Ethiopia (WPE).