The count in the Dublin Bay South by-election is under way.

Polling in the contest to replace Fine Gael TD and former minister Eoghan Murphy closed at 10.30pm on Thursday, with the count process commencing at the RDS the following morning at 9am.

The frontrunners – Labour’s Ivana Bacik, Fine Gael’s James Geoghegan and Sinn Fein’s Lynn Boylan – could face an anxious wait for the outcome, with the possibility that tallying will continue into the weekend.

That is because Ireland uses a system of proportional representation rather than the first-past-the-post election method (FPTP) used in the US and the UK.

The proportional representation with a single transferrable vote system, referred to as PR-STV or simply PR, allows voters to choose their candidate in order of preference.

The public write number one opposite their first choice candidate, two opposite their second, three opposite their third, and so on.

This way, voters whose chosen candidate is eliminated will have their vote transferred to their next preferred candidate.

The idea is that it maximises a person’s vote, with fewer votes discarded than in the FPTP system.

Turnout in the contest picked up on Thursday evening after a relatively slow start.

By around 9pm, the average voter turnout had reached 40%, compared to 34% at 8pm and 24% in the early evening, according to figures from RTE.

That is on a par with the last by-elections in 2019, when four contests saw turnout of between 25% and 35%.

But it remains well below the 2020 general election, when turnout was 62.9%​ nationally, and 52% in Dublin Bay South.

Thursday’s vote was Ireland’s first electoral contest since the pandemic began, but it remains to be seen if that impacted turnout.

A series of safety arrangements were put in place to ensure the by-election was held in accordance with Covid-19 public health advice.

Hand sanitiser was available at all polling stations, while voters were asked to wear masks and observe social distancing rules when inside.

Polling hours were extended by 30 minutes to assist Covid-19 arrangements, closing at 10.30pm instead of the traditional 10pm.

Other candidates include Deirdre Conroy of Fianna Fail, while councillor Claire Byrne is running for the Green Party.

The Social Democrats are represented by Sarah Durcan, while the People Before Profit candidate is Brigid Purcell.

The current TDs in the constituency are Fianna Fail’s Jim O’Callaghan, Sinn Fein’s Chris Andrews and Green party leader Eamon Ryan.

Long considered a Fine Gael heartland, Dublin Bay South is home to the affluent suburbs of Terenure, Rathmines, Rathfarnham and Ballsbridge.

The other candidates in Dublin Bay South are Justin Barrett (National Party), Jacqui Gilbourne (Renua), Mairead Toibin (Aontu) and independents Dolores Cahill, Peter Dooley, Mannix Flynn, John Keigher and Colm O’Keefe.