Fianna Fáil's high-profile health spokesman Stephen Donnelly is facing a tight battle to hold onto his seat.
Donnelly surged to an impressive poll-topping victory in the last general election as a Social Democrat representative.
However, his move to Fianna Fáil has severely dented his support and now finds himself competing for the final seat in Wicklow with Fine Gael junior minister Andrew Doyle.
If Donnelly loses, it would be a hugely disappointing performance for the party locally with the loss of two seats. Donnelly's party colleague, Pat Casey, has polled poorly and looks to be drifting out of contention.
On Sunday night, Sinn Féin’s John Brady was elected on the first count in Wicklow after topping the poll in impressive style.
The Bray-based politician, who in 2016 became Sinn Féin's first elected TD in Wicklow in 100 years, received more than 17,000 votes (24%), well in excess of the 11,000 quota.
Fine Gael's Simon Harris and the Social Democrats' Jennifer Whitmore, whose strong performance has exceeded local expectations, look set to take the second and third seats in this five-seat constituency.
The Green Party's Steven Matthews has also polled strongly and looks on course to take a fourth seat.
The battle for the final seat looks set to be determined by whether Fine Gael's Andrew Doyle can leapfrog Stephen Donnelly to avoid elimination.