Four into three won't go and in Dublin North Central that means that at least one sitting TD will lose his seat as boundary changes reduce it to a three-seater.
But it's more than four into three because at the end of the day four or five candidates will be chasing the final seat in what will be a fierce contest.
Dublin North Central has the distinction of being the only constituency on the north side of the capital to elect a Fine Gael TD when the party's vote collapsed in 2002. This is a reflection on the TD in question, deputy leader Richard Bruton, whose political ability and care for constituency matters is expected to see him top the poll this time.
A popular TD, Bruton is expected to get an increased vote as the party's only candidate, and if there is a surge for Fine Gael as the alternative coalition, all eyes will be on where his transfers go.
The constituency is losing a seat because of a shifting demographic with a smaller, ageing population, but it stands out for having a higher than average turnout at election time.
Dublin North Central was a Fianna Fáil stronghold, heartland of late former taoiseach Charlie Haughey, with current Minister of State SeáHaughey and former minister of state Ivor Callely as Fianna Fáil's incumbents.
Can the two hold on? It appears unlikely, and Callely looks the vulnerable one. He is, however, absolutely driven after the disaster of his forced resignation as minister 18 months ago.
In polite Fianna Fáil parlance there is "no formal vote-management agreement", which in reality means the gloves are off.
Callely is running a high-profile, all-out campaign for his political life to combat the Fianna Fáil slide in the polls, and he hopes the controversy over the painting of his Clontarf home is forgotten. He certainly can't be ruled out, although his Clontarf base is a volatile, middle-class locality whose loyalty no one can depend upon.
By contrast, Haughey's base in traditionally loyal areas like Donnycarney, Artane and Coolock, sympathy following the death of his father and his considerable work on the ground should see him through.
In seems the battle for the third seat will centre around Callely, and three "left" candidates; sitting Independent TD Finian McGrath, Labour's Senator Derek McDowell and the Green's Killester-based Bronwen Maher.
Sinn Féin's candidate is Peter Lawlor. He ran in the 2004 local elections and while the party polled a reasonable 5 per cent in this battleground he is effectively a "paper candidate". However, his transfers will be a crucial factor.
McGrath has an advantage over Labour and the Green Party of being the incumbent, and is helped that there are no other independent candidates. A consistent constituency worker whose campaigns include health and children with disability, McGrath has a major battle on his hands to survive, particularly after losing some of his base in the boundary changes.
McDowell, an articulate Seanad finance spokesman with a low-key presence on the ground, is buoyed by polls which show gains for Labour and the alternative coalition.
The Green tide was never really going to impact too much in Dublin North Central as an older community, but Maher is a transfer-friendly candidate and will certainly up her vote.
Verdict
FF - 1, FG - 1, Ind - 1
(loss for FF as four-seater becomes three)
