Enda Kenny will stand down as Fine Gael leader at midnight.
The Taoiseach has triggered the leadership contest to replace him at his parliamentary party in the last few minutes.
Mr Kenny's taken to twitter to announce the decision saying he will continue to carry out his duties as Taoiseach in full.
A new Fine Gael leader will be in place by close of business on the second of June - Simon Coveney and Leo Varadkar are the two leading candidates to replace him.
Cathaoirleach of Donegal County Council, Cllr. Terence Slowey has been paying tribute to the Taoiseach saying he did a lot for Donegal during his tenure: