Cormac lives in Dún Laoghaire with his wife Jennifer and their three young children.
He was first elected to Dún Laoghaire Rathdown County Council in 2004 and was subsequentlyre-elected in the 2009 & 2014 Local Elections.
In February 2016, he contested his first General Election where he received over 4600 first preference votes. Despite not being elected, he finished on 5564 votes.
Cormac was elected as Cathaoirleach of Dún Laoghaire Rathdown County Council at an Annual General Meeting of the Council on Monday 13th June 2016. This made him the first Fianna Fáil Cathaoirleach of the Council in 13 years and the youngest Cathaoirleach to service in that office.
Cormac is heavily involved in many local community organisations and volunteers with the following; Cuala GAA Dalkey,Beaufort Day Care Centre for the elderly, Glasthule, Dalkey Heritage Centre, Mounttown Community Facility, Southside Partnership, Sallynoggin College of Further Education,