Counting will get underway at 9am today in the by-election in Donegal South West.
Five candidates are vying for the seat, which was vacated by Fianna Fáil's Pat the Cope Gallagher in the European elections in June 2009.
The delayed by-election is the first chance voters have had to show their dissatisfaction with the Government since the economic crisis began.
It was Sinn Féin's Pearse Doherty who launched the successful legal challenge to force the Government to hold this delayed by-election. He is now favourite to win the seat here in Donegal South West.
There are four other candidates in the race, Fianna Fáil's Brian O'Domhnaill, Barry O'Neill of Fine Gael, Independent Thomas Pringle and Labour's Frank Mc Brearty.
Traditionally it is a Fianna Fáil's stronghold - the party had two TDs elected there in 2007.
If, as expected, Sinn Feéin's Pearse Doherty wins the seat, the Government's slim majority will be reduced to just two, assuming Independents Jackie Healy Rae and Michael Lowry continue to support the coalition.
Counting will get underway in the Finn Valley Athletic Centre in Stranorlar at 9am. Tallies are expected to give an indication of the result by lunchtime, with an result expected later in the afternoon.