Labour Party TD Seán Sherlock has announced he will not contest the next general election.
The Cork TD said it was a "difficult decision" that he made "with a heavy heart".
He said his decision was in part due to the recently re-drawn constituency boundaries, following the Electoral Commission's constituency review.
It saw 14,400 people in the Mallow region moved to Cork North Central from Cork East.
Mr Sherlock is based in Mallow. The change will see Cork North Central move from a four-seat to a five-seat constituency.
He said: “It would be wrong of me to pretend that the recent publication of the Electoral Commission’s Constituency Report 2023 has not influenced my decision.
“It has. The Commission had a difficult job to do, but the impact on Mallow and Cork East has been profound.
“I always anticipated some change to our constituency, but the scale of that change is so extensive that it caused me to reflect on my own political future.”
Mr Sherlock added: “I have never been afraid of a political challenge and have fought difficult elections successfully.
“However this time I had to weigh up the splintering of the areas I have represented and worked hard for over the last 20 years across two constituencies and the immense challenge of trying to get elected in an entirely new constituency.
“Having considered this with my wife, Máire, my family and my closest political supporters, and as a dad of three young children, I have decided that the time is now right for me to step aside.”
Mr Sherlock served as Minister of State in three departments during the Fine Gael-Labour Government between 2011 and 2016.
He is the second senior Labour TD to announce his plans to retire in the last week.
Former Labour Party leader Brendan Howlin has also confirmed he will not run in the next general election.
