All three Government parties will contest the by-election in Dublin Bay South after Fine Gael TD Eoghan Murphy resigned his seat.
The former housing minister announced his departure on Tuesday in a letter to party colleagues, and will take a role in international affairs.
The three coalition parties – Fianna Fail, Fine Gael and the Green Party – have signalled their intent to contest the vacant seat, with a by-election within six months.
Taoiseach Micheal Martin said: “Yes we will be contesting the by-election, which we didn’t anticipate.
“It’s quite an exciting by-election if you think about the potential personalities that always emerge from these contests.”
Tanaiste and Fine Gael leader Leo Varadkar said: “Fine Gael will contest the by-election and will contest it with a view to winning it.”
Green Party deputy leader Catherin Martin said: “We have to go through it with the electoral taskforce and the executive committee, but yes I would presume that the Green Party will contest it.”
Former Fine Gael TD Kate O’Connell, Dublin Lord Mayor and Green Party councillor Hazel Chu, and Sinn Fein senator Lynn Boylan are among those tipped to enter the race.
Ms O’Connell has been an outspoken critic of Mr Varadkar at times, but the Tanaiste insisted on Tuesday that he will support whichever candidate is chosen.
He said: “Under our party rules, the candidate is selected by the party members.
“Any party member in that constituency of more than two years standing has the right to vote. There’ll be one person, one vote, or rather one member, one vote.
“And those people… those hardworking members and activists for Fine Gael in Dublin Bay South know the potential candidates better than anyone else.
“I have no doubt that they will pick the best candidate, the one that’s most likely to win, and I support that candidate 100%.”
Ms Chu may face a struggle to get on the ticket after an ill-fated run in the recent Seanad by-election, against the wishes of her party.
While Ms Martin has supported the Lord Mayor’s Seanad bid, she declined to give overt support for her to run for the Dail.
She said: “It’s not for me, as deputy leader, to step into another constituency and decide to back someone. That would be inappropriate, because it’s not my constituency.
“I would like to see a woman elected in Dublin Bay South. That’s not an indication of support for any person, as I can think actually of three or four that jump out at me and they’re all female, in that constituency.”
