Santos was elected to Houston City Council, where he served for two years until his election as mayor. He served for four years (two terms of two years) as mayor, during which he opened four new healthcare clinics to serve Houston's families. As mayor, Santos also created a new housing assistance program to make rent more affordable for the city's two million residents. Santos was then elected to the United States House of Representatives during the 2000 midterm elections representing the 18th Congressional District and served for three terms. It was mentioned that during his third term as a congressman he had received a spot on the prestigious House Committee on Ways and Means, although he also served on the House Administration Committee ("the Siberia of committees") with then-congressman Bob Russell.