Complex sentence: He began his political career as a member of the Institutional Revolutionary Party (PRI), which he represented at the Chamber of Deputies of Mexico from 1994 to 1996 and as mayor of La Paz from 1997 to 1999.
Split into simpler sentences: He began his political career as a member of the Institutional Revolutionary Party (PRI). He served in the Chamber of Deputies of Mexico from 1994 to 1996 and as mayor of La Paz from 1997 to 1999.