Since January 1st 1980, twenty-four Dail by-elections have been held in the Republic of Ireland involving two hundred candidates who have won a combined total of 816,989 votes in these. Fianna Fail has been the most successful party in terms of winning votes in these by-elections (279,516 votes, or 31.9% of the total number of votes cast in by elections, marginally ahead of Fine Gael (250,648 votes, or 28.6% of the total number of votes cast in by-elections). The candidate who has won the biggest number of first preference votes in any by-election held during this period is George Lee (27,768 votes, or 53.4% of the vote, in Laois-Offaly 1984) , followed closely former Taoiseach, Brian Cowen (26,022 votes, or 54.7% of the vote, in Laois-Offaly 1984), but the late Cathal Coughlan (Donegal South-West 1983) is the candidate to win the highest vote share in any by-election during this period.

As noted above, Fianna Fail has been the most successful of the different parties/groupings in winning support levels at by-elections over the past three decades, although Fine Gael has managed to win as many (seven) of these contests as Fianna Fail has. Both parties contested each one of the twenty four by-elections held during this period. The share of the vote won by Fianna Fail in the first decade of this period (46.9%) is well in excess of that parties share of the by-election vote over the two following decades, with average support levels of 28.0% in 1990s and 22.9% in the 2000s. This can in part be explained by losses in by-election support during periods when the party was in government (and the party was in government for all bar two years during the 1990s and 2000s) but this is not the whole story here. Fianna Fail’s share of the vote in the 1982 by-elections (50.2% in Galway East, 39.7% in Dublin West), when the party was in government, compares well with its overall average, while the party’s share of the vote in the by-elections held during the period it was out of government in the 1990s tends to be lower than its overall average by-election support level. Fianna Fail won 40.1% of the votes cast in by-elections fought as a non-government party, against an average of 29.2% for by-elections fought as a government party. So overall loss of support is evident for periods when the party is in government, but there is an overall decline in Fianna Fail by-election support from the 1990s onwards.

The best performance by a Fianna Fail candidate in a by-election over this period was Cathal Coughlan’s 56.5% vote share in Donegal South-West 1983, while Fianna Fail candidates have also won more than 50% (and been deemed elected on the first count) on two other occasions: 54.7% in Laois-Offaly 1984 (Cowen) and 50.2% in Galway East 1982 (Treacy). The worst performance by any Fianna Fail candidate was Maurice Ahern’s 12.3% vote share in Dublin Central 2009.

Out of government the average Fine Gael by-election vote share (30.2%) tends to be larger than for periods when the party was in government (average of 23.4%), but the level of decline is not as evident as in the cases of Fianna Fail or Labour. Like Fianna Fail, Fine Gael’s 1980s by-election vote share (34.6%) tends to dwarf that of its average vote share during the 1990s (22.0%) and 2000s (32.4%), with the growing strength of non-party and smaller party candidates during this latter period eating into the two main parties’ vote shares. George Lee won the most votes, and largest vote share, of any Fine Gael candidate in a by-election. The next largest number of votes won by a Fine Gael by-election candidate,s ironically, were won by losing candidates; Dinny McGinley won 20,022 votes when finishing in second place in the 1980 Donegal by-election and Padraig Horan won 18,173 votes in Laois-Offaly 1984 when finishing 2nd behind Brian Cowen.

The Labour Party trails some distance behind these other parties, having contested every by-election bar Donegal 1980 and Donegal South-West 1983 and accounting for 99,084 votes or 11.3% of the total by-election valid votes over this period. Being in government seems to adversely influence the Labour by-election vote to an ever greater degree than Fianna Fail. Out of government the average Labour by-election vote share (14.4%) is significantly larger than for periods when the party was in government (average of 6.7%). However, unlike Fianna Fail and Fine Gael, Labour’s by-election vote share improved in recent decades, with its dismally low 1980s by-election vote share (2.5%) being decidedly lower than the share of the by-election vote won in the 1990s (14.6%) and 2000s (15.0%). Sean Ryan accounts for the biggest by-election vote share of any Labour candidate, winning 11,012 votes (33.3%) in the 1999 Dublin North by-election. The lowest vote won by any Labour candidate was the 703 votes (1.6%) for Brendan O’Sullivan in Dublin West 1982.

Sinn Fein candidates, who contested just over half (13) of the by-elections held since 1980 won 38,425 votes (with Doherty’s 2010 Donegal South-West vote accounting for well over one third of these) and 4.7% of the total valid by-election votes cast during this period.

Green Party candidates contested the same number (13) of the by-elections held since 1980 as Sinn Fein did, but won fewer votes, winning 25,300 votes or 3.1% of the total by-election votes cast during this period. Despite contests being held in constituencies (Dublin North, Dublin South) where the party held seats at the time of a by-election, the party’s two best by-election performances are both accounted for by Dan Boyles in his 1994 and 1998 Cork South-Central by-election contests, with Boyle winning 6,677 votes (15.8%) in the 1994 election. Apart from Boyle, no other Green candidate has won more than two thousand first preference votes or 7.0% of the total votes in any by-election contest.