A crucial by-election test for the parties in Carlow/Kilkenny

A telling outing in advance of General Election

The marriage equality referendum may generate intense public interest next week but politicians will concentrate on assessing the implications of the Carlow/Kilkenny by-election. Broad inter-party agreement exists on support for a "yes" vote, but the outcome of the by-election may threaten political careers; unhinge alliances and point the way towards a general election outcome. Fianna Fáil's Bobby Aylward was installed as the hot favourite to take this seat. But a decision by Renua to recruit former Fianna Fáil councillor Patrick McKee as its candidate complicated matters. In recent days, Fine Gael has begun to promote the prospects of David Fitzgerald while Sinn Féin's Kathleen Funchion is said to be doing well in the Carlow area. In line with these developments, bookmakers have shortened the odds on high-profile contenders but Mr Aylward remains the favourite.

Carlow/Kilkenny has recently witnessed dramatic shifts of political allegiance. In 2011, support for Fine Gael jumped ten points to 39 per cent; Fianna Fáil dropped to 28 per cent; Labour Party support rose to 16 per cent and Sinn Féin's to 9.5 per cent. Those changes were based on a catastrophic 20-point fall in support for Fianna Fáil. For decades, the party has dominated this constituency. On that basis, should Mr Aylward fail to recover his Dáil seat, criticism of Michael Martin's leadership may spill over into open revolt. The performance of Patrick McKee in Renua's first electoral outing will be an important indicator of public support, affecting not just the party's fundraising efforts but its long-term prospects. The growth of Sinn Féin; the impact of its policies and the performance of Ms Funchion will also be closely monitored in view of that party's ambition to lead an alternative government.

In the aftermath of the UK general election and a surprise win by the Conservatives, hope has revived within Fine Gael and the Labour Party. Similarities exist between the two campaigns, but there are clear-cut differences. The Government parties are promoting the benefits of a recovering economy that was seriously damaged by Fianna Fáil. They are handicapped, however, by unpopular taxation measures and uneven economic growth. Moderate Fianna Fáil criticism of water charges is being trumped on by-election doorsteps by Sinn Féin’s commitment to abolish them, along with the property tax, while reducing the Universal Social Charge. At issue is how the electorate responds to such blandishments.

Having regained a Dáil seat, before being hammered in the local elections, Labour Party expectations are low. But Willie Quinn’s performance will be scrutinised for evidence of a gradual recovery. Fine Gael will look to David Fitzgerald to confound the bookmakers and produce a surprise result. All parties – and their leaders – are under pressure. A general election approaches.