Officials in Castlebar have begun rechecking votes in the Midlands Northwest European constituency.
Just 275 ballots separate two candidates - Independent Marian Harkin and Fianna Fáil's Pat the Cope Gallagher - for the fourth and final seat.
Harkin stands on 106,520 votes with Gallagher on 106,245.
Independent Luke Ming Flanagan, Fine Gael's Mairead McGuinness and Sinn Féin's Matt Carthy have already been elected.
The returning officer for the MNW European constituency Fintan Murphy confirmed just before midnight last night that a recheck of votes will take place.
"A recheck is where they take out the bundles of votes and you see where the 1, 2, 3 is etc." Ms Harkin explained.
"If there is a discrepancy - if there is a vote in there that shouldn't be there - then they photocopy that vote and they tag it.
"And then that's put aside.
"And when that process is completed they will know if there is any material difference between the candidates."
Fianna Fail's Director of elections for the European constituency, Timmy Dooley, said the party is sending representatives to Castlebar to oversee the recheck process.
"Well my understanding is that we'll have a team of people who will be here to scrutinise every ballot on behalf of Pat 'The Cope' Gallagher - and I expect that'll be the same for the other remaining candidates as well," Mr Dooley said.
"It's just to make sure from our perspective that the people who have cast their ballot for Pat 'The Cope' Gallagher and for Fianna Fail it's reflected in the ultimate result, and of course we'll accept the outcome without hesitation."