Married with two children, he belongs to the State Bodies of Senior Tax Inspectors and Senior State Administrators Marugán entered national politics at the 1982 General Election when he was elected to the Spanish Congress of Deputies representing Seville Province.

Marugán has usually been identified with the "Guerrista" sector of the PSOE (which takes its name from the veteran deputy Alfonso Guerra) and in a 2005 article supported Guerra in criticising the actions of the PSOE such as entering into a tripartite Government in Catalonia.

[1] He is also considered a close associate of former president of Extremadura Juan Carlos Rodriguez Ibarra, also identified with the Guerrista sector.

[3] Following the narrow PSOE victory at the 1993 election he served as Secretary of State for Economic and Social issues in the last PSOE government of Felipe Gonzalez which lasted until the 1996 election.

[4] In 1999 Marugán became involved in a shouting match with the Partido Popular minister Josep Piqué in the Spanish Congress chamber which ended with Piqué calling Marugán a "hijo de puta" (son of a bitch).