With the Dublin West by-election scheduled to take place on the same day as the Presidential Election, this is a good time to review statistics for voting patterns in recent by-election contests. This post, reviewing such patterns in the 23 by-elections held since 1980, shows that government parties have attained little in the way of success in such contests over the past three decades, with Noel Treacy (Galway East 1982) emerging as the only government party candidate to win a by-election over this time period.

Comparing constituency support levels for government parties in these by-elections, but also the general elections immediately before and after those contests, shows that government party support levels invariably fall at a by-election contest although usually recovering somewhat (to varying degrees depending on the political context) at a subsequent general election contest in the same constituency.  Between 1980 and 2011, government party candidates won, on average, 31.8% of the first preference votes cast in by-election contests, contrasting with the average support level of 47.3% won by those parties in the same constituencies in the general election held prior to the by-election. This represents a drop in support levels at by-election contests for government parties by 15.5% on average.  Support levels for government parties are shown to generally recover somewhat at the following general election in the same constituencies, although there are a number of exceptions here, including most of the 1980s by-elections, as well as the 1996 Donegal North East and 2009 Dublin South contests. The average support level for government parties in these contests at the subsequent general election amounted to 36.7%, on average, representing an increase by almost five percent, on average, relative to those parties’ by-election performances.

Ironically the most successful period for government parties in terms of by-election performances was the GUBU period of 1982, when a Haughey-led Fianna Fail succeeded in retaining their seat in Galway East (with Treacy exceeding the quota on the first count despite a 4.9% drop in Fianna Fail support levels in the February 1982 general election) and the party also came close to taking a seat off Fine Gael in Dublin West. In the Dublin West contest (the background to which probably warrants a number of separate posts!!!) Fianna Fail support only dropped by 2.0% relative to the February election – statistically the best performance by a government party candidate – as their candidate, Eileen Lemass, topped the poll some 328 votes ahead of Fine Gael’s Liam Skelly, but ultimately lost out on the seat due to transfers.

The least successful government in terms of by-election performances was the Brian Cowen led Fianna Fail-Green Party-Progressive Democrat* government performances in the three by-elections held during the lifetime of that government – two in 2009 and one in 2010. In all of these contests, government party support levels fell by more than thirty percent relative to their results in the preceding election, dropping by 30.7% in Donegal South-West 2010, 35.6% in Dublin Central 2009 and 36.5% in Dublin South 2009. (Dublin South represents the worst ever performance by government parties in a by-election over the past three decades and to make matters worse the support levels for government party candidates fell by a further 5.1% at the subsequest general election contest in that constituency.) Naturally, government party candidates were not in contention for seats in any of these contests (and indeed no government party candidate succeeded in winning a seat in any of these constituencies in the February 2011 election) although Brian O Domhnaill did succeed in finishing second on first preference votes in Donegal South-West before being overtaken by Fine Gael’s Barry O’Neill on the basis of transfers.

Table 1: Average support levels for government parties in by-elections

Offering some consolation to the Fine Gael and Labour candidates is the fact that, on average, government party candidates tend to poll best in by-election contests held during the first year of their government’s terms in office, when they presumably may be enjoying a honeymoon period. The average level of declining support at by-elections in these cases was just 8.8%, contrasting with the average level of decline of 15.5% for all by-election contests. The Galway East by-election win by Fianna Fail in July 1982 fell within the first five months of that, admittedly short-lived, government’s term in office. As Table 1 above shows government parties are likely to perform best in by-elections if these are held in the first year, or honeymoon phase, of that government’s term in office. The worst time for government parties to face by-elections is during the middle of that government’s term in office, with average support levels being much lower than what these parties may expect to win in the first or last year of that government’s term in office.  

At a regional level, government parties tend to perform worse in by-elections in Dublin than in any other region, as Table 1 above shows, with the best government by-election results associated with the Leinster region.

So why do government parties fare so poorly at by-election contests? Anger or disappointment at government party performances may be one factor. This ties in with the second-order election model, which argues that at election contests (such as by-elections, European elections etc.) which voters perceive to be less important than first-order elections (e.g. general elections) voters will be more likely (a) not to vote, (b) to vote against government party candidates, even if they are government supporters, to ‘safely’ send a message to the government. Another factor explaining a drop in government party support (and applying in the cases of Fine Gael and especially Fianna Fail) relates to number of candidates – if that party has run three or four candidates in a preceding general election it is probably not too surprising that their support level will drop at a by-election where only one party candidate is contesting. Moreover, while Fine Gael or Fianna Fail will expect to poll very well in the areas where their by-election candidates are based, the party’s vote share would probably decline in other areas of the constituency, which might have had a strong local candidate from those parties competing in the general election. Finally, if the local electorate may feel that a government win will leave too many government party TDs in the one constituency they may opt to vote against that party in the by-election as a result; this it could be argued could have been a factor in the 2005 Meath by-election where a win for Fianna Fail’s Shane Cassells would have left Fianna Fail with four of that constituency’s five TDs.