For a quarter of a century, Fianna Fáil was the dominant political force in Meath. From 1987 to 2002, the party held three of the five seats; in 2007, when Meath was split into two three-seaters, Fianna Fáil took four of the six seats.

That all changed in 2011, when Fianna Fáil could not win a single seat in either Meath constituency.

In Meath East, its share of the vote dropped from 43.6% (2007) to just 19.6% (2011) – down 23.9 points.

RTÉ Political Correspondent David McCullagh believes the battle for Meath East could come down to a two-horse race between Fine Gael and Fianna Fáil 

At the same time, support for Fine Gael soared, up 15 points to 40.9%, doubling its number of seats to two, held by Shane McEntee and Regina Doherty.

Labour took the third, after Dominic Hannigan almost doubled his vote – from 11.9% in 2007 to 21%.

Sinn Féin more than doubled its support, from a low base – from 3.9% in 2007 to 8.9% in 2011.

For Labour, the big challenge is to avoid being beaten into fourth place – behind Sinn Féin – or even fifth, behind Ben Gilroy of Direct Democracy, who is reported to be doing well on the ground.

Third place, and a share of the vote over 12% or 13%, would be a very good result for Labour. It’s also highly unlikely.

Labour sources have been busy pointing out that in the Dublin West by-election, Fine Gael were beaten into fourth place, behind Labour, FF and the Socialist Party. Damage limitation is go!

Sinn Féin claims to be “in it to win it”, but nobody believes them. Another significant increase in support will do them nicely, setting Darren O’Rourke up for a tilt at a seat in 2016.

Given recent opinion poll results, anything less than third place and support in double figures would be a set-back.

Fine Gael have a number of advantages: Shane McEntee was very popular, and the tragic manner of his death has generated great sympathy, which his daughter Helen should benefit from; the party was way out ahead in 2011, with 40.9% of the vote; shorter polling hours – and the weather – will drive down turnout in the southern end of the constituency, the commuter belt where anger against the Government is highest; by contrast, turnout seems to be stronger in the McEntee heartland in the north of the constituency.

Anything less than a win would be a setback for Fine Gael.

Despite the apparent advantages for Fine Gael, this should be very winnable for Fianna Fáil.

Bear in mind that Labour’s victory in Dublin West was the first by-election win by a Government party in almost 30 years (since Noel Treacy won Galway East in 1982); Fianna Fáil has been doing well in opinion polls lately, and should certainly do a lot better than its disastrous 2011 showing; and in Senator Thomas Byrne – a former TD for the constituency – they have the candidate with the most Oireachtas experience, as well as significant name recognition.

To prove that recent opinion poll results aren’t a flash in the pan, the party must secure a significant increase in its vote share; while they could live with coming a close second to Fine Gael, Fianna Fáil will be hoping to win a by-election for the first time in 17 years.

The party’s last successful by-elections were on 2 April, 1996, when Cecelia Keaveney in Donegal North East and the late Brian Lenihan in Dublin West won seats for Fianna Fáil.