Lahiffe was elected to Dáil Éireann at the 1948 general election as a Fianna Fáil TD for the Galway South constituency. He was defeated at the 1951 general election by Fine Gael's Patrick Cawley, but two years later was re-elected at a by-election in August 1953 following the death of Frank Fahy, a Fianna Fáil TD who as Ceann Comhairle had been returned unopposed in 1951. Lahiffe held the seat at the general election in 1954, but was ousted again at the 1957 general election. Fianna Fáil had run three candidates in three-seat constituency, and Lahiffe was beaten by his first-time running-mate Michael Carty.
- "Robert Lahiffe". Oireachtas Members Database. Retrieved 8 January 2008.
- "General Registrar's Office" (PDF). IrishGenealogy.ie. Retrieved 17 August 2018.
- "Robert Lahiffe". ElectionsIreland.org. Retrieved 8 January 2008.
- "General election: 5 March 1957 – Galway South". ElectionsIreland.org. Retrieved 8 January 2008.