Voters go to the polls on Friday in the biggest test for parties ahead of the General Election. Politicians from all sides will be battling to win seats in Dublin Mid-West, Dublin Fingal, Cork North-Central and Wexford to fill vacancies following the departure of Frances Fitzgerald (FG), Clare Daly (Independents4Change), Billy Kelleher (FF) and Mick Wallace (Independents4Change). The four big names won seats in the European Parliament in May. Paul Cunningham looks at the lie of the land in Dublin Mid-West and assesses who is likely to come out ahead.

Dublin Mid-West

There are 13 candidates contesting this by-election:

David Gardiner Workers' Party; Paul Gogarty Independent; Emer Higgins Fine Gael; Peter Kavanagh Green Party; Charlie Keddy Independent; Peter Madden Independent; Anne-Marie McNally Social Democrats; Shane Moynihan Fianna Fáil; Ruth Nolan Independents4Change; Kellie Sweeney Solidarity/People Before Profit; Francis Timmons Independent; Joanna Tuffy Labour Party; Mark Ward Sinn Féin. 

Reason for by-election

The election of the Fine Gael TD Frances Fitzgerald, a former Tánaiste and Minister for Justice, to the European Parliament last May.  

Interesting because....

It is the only one of the four by-elections taking place in which Fine Gael is defending a seat. While Fine Gael views Dublin Mid-West as a contest it has a strong chance, the other parties and Independents feel a transfer friendly candidate can win.

Lie of the land

This is a constituency which is about to change dramatically - with an estimated 20,000 people set to move into a new town, Clonburris, and follow in the footsteps of Adamstown. Older town centres in the constituency are Lucan, Clondalkin, Palmerstown, Saggart and Rathcoole. The population is around 110,000. 

Election issues

Housing is a big issue. Transport is also a significant cause for concern in this commuter belt. Anti-social behaviour regularly comes-up on the doorsteps. 

Electoral certainties (insofar as they exist)

If Fine Gael does not retain this seat, it would further weaken and destabilise the minority-led Government. 

Likely to be elected

The front runners are Councillor Emer Higgins of Fine Gael; former Green Party TD but now Independent Councillor Paul Gogarty; and Sinn Féin Councillor Mark Ward. All three topped their wards in the Local Elections in May. 

Electoral battle

Fine Gael was the most popular party in this four-seat constituency in the 2016 General Election, when it won 26% of the first preference vote. However Sinn Féin wasn't far behind with 22% and its TD, Eoin Ó Broin, topped the poll. That's why much of the media focus has been on Councillor Emer Higgins and Councillor Mark Ward. However, Paul Gogarty retains name recognition from his time as a TD between 2002 and 2011, and also has the ability to tap into any green wave which may emerge. 

Higgins looks likely to top the poll this time. If that happens, the two big questions will be how large is her advantage and what capacity does she have to attract transfers. Sinn Féin is putting in a huge effort in Dublin Mid-West to ensure its supporters turn-out to vote. While Sinn Féin had a poor Local Election result in May - it held its strength in Dublin Mid-West. Independent Paul Gogarty has a smaller campaign team, but is better known than the other two leading candidates.

Another determining factor will be where the votes of sitting People Before Profit TD Gino Kenny go. Kellie Sweeney, a nurse, is campaigning hard for the party. However, it will be difficult to get her message across, given the crowded field on the left. Two candidates expected to poll well would be former Labour TD and now Councillor Joanna Tuffy, and the Social Democrats big hope Anne-Marie McNally - who came fifth in the 2016 general election battle with more than 2,600 votes. First time Dáil candidate for the Greens, Councillor Peter Kavanagh, and Councillor Ruth Nolan of Independents4Change, will also be hunting for votes in broadly the same pool.

The Fianna Fáil standard bearer is Councillor Shane Moynihan. The sitting Fianna Fáil TD, John Curran, secured a substantial 16% of the first preference vote in 2016. However, Moynihan garnered less than half of Sinn Féin Mark Ward's vote in the Locals in Palmerstown - Fonthill, suggesting it will be an uphill struggle for him to be in the final shake-up this time round. Three other Independents in the race, Charlie Keddy, Peter Madden and Francis Timmons, as well as David Gardiner of the Workers' Party, would need luck to go their way to feature strongly in this hard fought contest.

So the first count in the Dublin Mid-West constituency will tell a lot: Can Higgins secure enough first preference votes to give her an unassailable lead? If not, how close can Sinn Féin's Mark Ward get to her? Can Paul Gogarty manage to use his name recognition to his advantage? Or will one of the centre-left candidates put themselves into an advantageous position and pick-up the lion's share of transfers as others are eliminated.

With a General Election due in around six months' time, a significant block of the electorate may simply stay at home. What that means for the eventual outcome is anyone's guess.