Minihan entered local politics in 1999 when he was elected to Cork City Council for the Progressive Democrats (PDs). In July 2003 he was elected Chairman of the Progressive Democrats.
He unsuccessfully contested the 2002 general election, where he polled 3,126 first preferences votes in the Cork North Central constituency.[1] He was a member of the three-man team representing the Progressive Democrats which negotiated the terms under which the party entered government in coalition with Fianna Fáil.
Subsequently, he was recommended by Mary Harney, Progressive Democrats party leader and Tánaiste, Minihan was nominated by the Taoiseach Bertie Ahern to the Seanad, where on the 12 September he made his maiden speech speaking on the Treaty of Nice.[2]
He worked in a number of committees and jobs including Chair of the Progressive Democrats parliamentary party. He was coordinator of the Oireachtas Joint Houses Friends of Science Committee. He served as a member of the Joint Oireachtas committees on Education and Science, and party spokesman on Education, Defence and Childcare.
On the abolishment of dual mandate in 2003, he resigned his seat on Cork City Council which was filled by co-option. The party seat was not retained by the PDs in the 2004 local elections. In January 2006 he was selected to run for a Dáil seat as a Progressive Democrats candidate in the Cork South-Central at the 2007 general election, but did not win a seat, getting 1,596 first preference votes. He was not returned to the Seanad in the 2007 Seanad election. Minihan is retired from politics.