Martin McAleese, husband of the former President, has informed the Government that he wishes to resign his seat in the Seanad.
The formal announcement that he has departed the Upper House is expected to be made in the Seanad next week.
Mr McAleese was appointed to the Seanad as one of the nominees of Taoiseach Enda Kenny in May, 2011.
Shortly after his appointment to the Seanad, Mr McAleese was asked to chair the committee investigating the Magdalene laundries and has been heavily occupied in that work.
He has been an infrequent participant in Seanad debates and has voted only once, in opposition to the budget cut in the respite grant.
Mr McAleese's wife is currently living in Rome where she is studying canon law.
During his 14 years as the spouse of the president, Mr McAleese adopted a very active role in furthering the Northern Ireland peace process.
In particular he built up a range of contacts with loyalist paramilitaries in Northern Ireland and was widely credited with helping to create the conditions for the loyalist ceasefire.
Mr McAleese campaigned for aid in the reconstruction of disadvantaged loyalist communities and his work won goodwill in the loyalist heartlands and helped in the process which led to the UDA decommissioning its weapons in January, 2010.
More recently he has chaired a committee of officials from five Government Departments who have been conducting the inquiry into the Magdalene laundries.
That report has been completed and will be presented to the cabinet next Tuesday morning. It will be published later in the day.
In his resignation letter, Mr McAleese said: "During my time in the Seanad I dedicated myself to two main projects. The first, chairing the inter-departmental committee's investigation into State involvement with the Magdalen Laundries and the second, continuing the work of bridge building between North and South."
"I am pleased to tell you that the report on the Magdalen Laundries, which Minister Shatter asked me to undertake, has been completed after some eighteen months of intensive research and analysis and is shortly to be published. It is my fervent hope that the Report will be of real public service most especially to the women concerned."
"I am particularly grateful for the way in which the Seanad contributed to a number of bridge-building initiatives, most particularly its historic invitation to the Orange Order. The success of that ground- breaking initiative augurs well for the continued, steady consolidation of peace and good neighbourliness between those who share this island."
