Fine Gael front-bench member Mr Ivan Yates is expected to announce his retirement from politics at noon today after a 20-year career in the Dail, including 2 1/2 years as Minister for Agriculture.
Mr Yates, a close supporter of defeated party leader Mr John Bruton, is expected to cite pressure of business and family life as the reasons behind his decision. The 41-year-old is believed to want to spend more time on the growing family business involving a chain of betting shops.
While he is expected to stress his decision does not reflect on whoever wins Friday's party leadership contest, his decision to quit politics has been accelerated by Mr Bruton's defeat.
Mr Yates had said last year he would quit politics by the time he was 50.
Although he staunchly backed Mr Bruton during last week's heave, Mr Yates could have expected to be appointed to the party front bench - and to cabinet in a Fine Gael-led government - irrespective of who replaces Mr Bruton. The reasons for his decision to quit now are therefore unclear.
Mr Yates defended Mr Bruton throughout various difficulties in his time as party leader. He performed a similar supporting role for Mr Alan Dukes during his period as leader from 1987 to 1990.
He was not available for comment yesterday. However, he has spoken in the past of the difficulty in balancing a demanding political career with family life and the family business.
He was deeply disappointed by Mr Bruton's defeat last week and announced immediately afterwards he would not serve on the next front bench no matter who became leader. He also said he would not participate in any of the leadership campaigns and has not disclosed who he would be voting for in that contest.
His decision robs Fine Gael of one of its most able performers and it may also create difficulties for the party in Mr Yates's Wexford constituency.
Mr Michael Darcy may be the sole sitting deputy on the Fine Gael ticket in the five-seat constituency unless Ms Avril Doyle, a Senator and MEP, decides to contest the next general election. She is not expected to do so as it is believed she will concentrate on her role in the European parliament. It is not known whether Mr Yates's decision will change this.