Fine Gael TD Olivia Mitchell has written to party members this morning announcing her decision to step down ahead of the General Election.
"I believe now is the right time for me to pass the mantle to a new generation," Ms Mitchell said in the letter, seen by Independent.ie.
"While this was a difficult decision for me to make, I am consoled by the knowledge that we have in the constituency a number of excellent potential candidates who are more than qualified to retain the seat for Fine Gael," she added.
Ms Mitchell's decision has surprised party members and created a dilemma for headquarters over the approach towards candidate selection.
Party sources fear the other sitting TD, former justice minister Alan Shatter, will be defeated at convention.
Prominent councillors Neale Richmond, Josepha Madigan and Barry Saul are all expected to run.
In a statement today, Ms Madigan said:
“Olivia has been a tremendous representative for her constituents for almost 20 years. She has also been a role model for women looking to enter politics, including myself.
“She has been very influential in my political career, giving me invaluable advice and support during my successful council election campaign last year.
“I hope to continue her good work and if selected to contest the general election for Fine Gael, I know that I can count on her support.”