The announcement came a day after Kenny said he would quit, kicking off a succession contest that was confirmed as a race between two younger ministers after other potential candidates stepped aside and colleagues began to pick sides.
Front runners to replace Mr Kenny as Fine Gael leader and subsequently become Prime Minister include social protection minister Leo Varadkar and housing minister Simon Coveney.
Supporters of Varadkar last night claimed their man has the charisma to be the country's next leader - as Simon Coveney insisted: "People are not looking for a Taoiseach with an X factor".
"I will continue to carry out my duties as party leader in an acting capacity, until my successor is elected through the Fine Gael leadership election process", he said.
In a statement announcing his retirement as leader, Mr Kenny said it had been a "huge honour and privilege" to steer the party over the course of 15 years.
Irish Prime Minister Enda Kenny speaks to the media at the general election count centre in Castlebar, Ireland February 27, 2016.
The Taoiseach delayed the transition to a new leader, allowing him to attend the annual St Patrick's Day celebrations in the USA and meet President Donald Trump.
Kenny is the longest serving TD in Leinster House he has been a member of Dail Eireann since 1975.
He said: "I believe that I can modernise and transform Fine Gael, making it a campaigning party and a force again".
Enda Kenny speaks at a luncheon hosted by the Chamber of Commerce of Metropolitan Montreal during his visit to Montreal, Quebec, Canada May 4, 2017.
Senator McFadden said Varadkar and Coveney were "high-calibre candidates and very capable guys" but she would be supporting the Cork man as she believed he was best placed to suceed on behalf of Ireland in the Brexit negotiations.
He will act as interim leader until then and has indicated that he will give his successor a "brief but appropriate" period to negotiate with the rest of the Dáil to secure a government going forward.
The contest is decided by an electoral college with the parliamentary party worth 65% of the total vote, rank-and-file members accounting for 25% and 235 local representatives making up the remaining 10% of the vote.