[5] He subsequently joined Fine Gael for similar reasons, this time inspired by the anti-Sinn Féin stance of that party's then leader, John Bruton.

[5] In December 1995, he was nominated by the Taoiseach, John Bruton, to the 20th Seanad, where he was appointed government spokesperson on the Environment.

In a reshuffle of the Fine Gael front bench in June 2000, Hayes was promoted as spokesperson on Northern Ireland.

[8][9] The Irish National Teachers' Organisation (INTO) described the idea put forward by Hayes as "discriminatory, inequitable and deeply flawed".

In October 2010, he was appointed as party Deputy spokesperson on Finance with special responsibility for Public Expenditure.

[18][19] Hayes publicly acknowledged that Ireland had suffered reputational damage following the death of Savita Halappanavar, the pregnant Indian woman who died after being denied an abortion at University Hospital Galway.

[21] Hayes was the lead negotiator for the European People's Party (EPP) on the plan for a Pan-European Pension Product (PEPP).