Last time around: In 2011, Sinn Féin won 14 seats with a 9.94% share of the vote.
Last local elections: In the 2014 local elections, Sinn Féin won 159 council seats with a 15.2% share of the vote.
Best case scenario: The party wins more than 26 seats. It picks up two seats in Louth, and a further two in Cavan-Monaghan. Constituencies such as Wexford and Tipperary also return a Sinn Féin candidate.
Worst case scenario: Sinn Féin has managed to secure middle class votes in Northern Ireland but one of the party's challenges in the South has been to secure that vote. Its core support is rock solid but it needs to attract softer support and floating voters. If this does not happen and the old mantra that Sinn Féin does not do as well in elections as it does in the polls is borne out, the party could remain at around 15-16 seats on a bad day.
Expected outcome: Already on 14 seats, Sinn Féin looks well poised to add seats in constituencies such as Dublin Mid-West, Sligo-Leitrim, Limerick City, Carlow-Kilkenny, Wicklow and Dublin West to win seats. It could be on course for in the region of 23-26 seats.
Leader profile: Provo, peacemaker, parliamentarian, prolific tweeter – Gerry Adams is a contradictory and controversial figure. His place in Irish political history has already been established but how far he will take Sinn Féin in electoral terms in the Republic is less clear. Read the full profile here.
By Conor McMorrow, RTÉ's Political Staff
