Sinn Féin TD Jonathan O'Brien will not contest the imminent next general election after taking time in recent months to "pursue new personal opportunities".
Mr O'Brien told RTÉ News he will not seek to retain his Cork North Central seat, meaning three of the constituency's four TDs elected in 2016 will not contest the coming vote - throwing the race open for other rival parties.
In a statement tonight, Mr O'Brien said: "I am announcing today that I will not be contesting the next general election. This has been a difficult decision for me to make and it is one that I have made after several months of consideration.
"I have had the great privilege and honour to serve the people of Cork for 20 years as a Sinn Féin elected representative, first as a member of Cork City Council for 11 years and the last nine years as a TD.
"In that time I have contested seven elections on behalf of Sinn Féin and I want to thank the voters for giving me the opportunity to represent them.
"After two decades, I feel the time is right to pursue new personal challenges and opportunities."
RTÉ News understands that in recent months Mr O’Brien had been considering whether to remain as a TD due to his length of time in politics, a decision which was exacerbated by the recent death of his mother.
Mr O’Brien has also been studying for a law degree at University College Cork since September, which he will take up full time after he steps down as a TD.
It is understood Mr O'Brien and Sinn Féin leader Mary Lou McDonald spoke about the Cork TD's plans to leave in the autumn, during which both politicians agreed he would delay the decision until after last November's by-election.
During that by-election - ultimately won by Fianna Fáil's Padraig O’Sullivan - Sinn Féin councillor Tommy Gould finished a respectable third with 19.7% of first preferences.
This strong showing further convinced Mr O’Brien to leave at the end of this Dáil term.
Mr O'Brien's decision to step down means three of the four TDs elected to represent Cork North Central in 2016 will now not contest the imminent general election.
The other two are Fianna Fáil's Billy Kelleher, who won a European parliament seat last May, and Fine Gael TD Dara Murphy, who controversially step down as a TD late last year.
While no decision will be made until a selection convention on Saturday 18 January, Tommy Gould has been predicted to be one of few names to be put forward to contest the seat for Sinn Féin.
The Cork North Central constituency has been consistently split between Sinn Féin, Fianna Fáil, Fine Gael and Solidarity-PBP Mick Barry in recent years, in part due to its sprawling urban-rural nature and its strong working class areas.
However, with Mr O’Brien, Mr Kelleher and Mr Murphy - the first two of whom had strong personal votes - not running, it is unclear if this split will remain the same.
In a statement responding to Mr O’Brien's announcement, Ms McDonald thanked her colleague for his "20 years service".
"Jonathan has served his constituents and Sinn Féin with distinction as a member of Cork City Council for 11 years and for nine years in the Dáil.
"During that time he has earned a reputation as one of the strongest and most genuine voices in Irish politics.
"Someone of Jonathan's talent and calibre will undoubtedly be missed as a public representative.
"But I know that Jonathan will remain a proud and committed member of Sinn Féin and will work to retain the Sinn Féin seat in Cork North Central and contribute to the party in other ways into the future," added Ms McDonald.