The Labour candidate, Dr Mary Upton, is expected to retain the party's seat in the Dublin South Central constituency left vacant by the death of her brother, Pat. That would be the fourth by-election defeat in a row for Fianna Fail since it came to power.
The decision to run Dr Upton (53), a food scientist and director of elections for her late brother, has created its own headaches for the Labour Party's shared leadership. The former Democratic Left TD for the constituency, Mr Eric Byrne, desperately wanted the nomination, and internal party bickering over who was to contest the by-election reflected the division remaining in the constituency following the merger of Labour and DL.
In the end, Mr Byrne agreed not to contest the selection convention in return for a guarantee that he would be one of the Labour candidates in the next general election. South Central will then be expanded to a five-seater taking in parts of Ballyfermot, Inchicore and Kilmainham.
Given that the constituency already has a huge working-class base including Fatima Mansions, Dolphin's Barn, Walkinstown, Drimnagh and Crumlin, Labour says there will be two seats there for the party next time.
However, the constituency also includes at its southern end the middle-class areas of Templeogue and Terenure.
The late Dr Pat Upton, originally from Clare, came from nowhere to record the fifth-highest Labour vote in the State in the 1992 election, when the party picked up new seats all over the State. Then a DL candidate, Mr Byrne failed to take a seat that time after the famous cliff-hanging 10-day recount: he lost out to Fianna Fail's Mr Ben Briscoe by a heart-breaking five votes. But he won the by-election in 1994 following the retirement of Dr John O'Connell.
Although he was 350 votes ahead of Dr Upton after the first count in the 1997 election, Mr Byrne eventually lost.
Dr Mary Upton is confident that she will take the seat on October 27th, but the party acknowledges that the support of Mr Byrne and his loyal team will be needed to ensure victory.
While there is no great evidence of this to date, it is early days yet and the party is confident that Mr Byrne and his workers will turn out to support the Labour candidate.
This is very much a two-horse race, with the only real threat to Dr Upton coming from the Fi anna Fail candidate, city councillor Mr Michael Mulcahy.
A former senator and a barrister, Mr Mulcahy is no stranger to the hustings. He unsuccessfully contested the 1992 and 1997 general elections and the 1994 byelection. He was nominated to the Seanad by Mr Albert Reynolds in 1994 and served as the party's spokesman on justice there until 1997. Mr Mulcahy will undoubtedly be cashing in on his recent local election success. He polled 1,733 first preferences to be re-elected to Dublin Corporation in the Crumlin-Kimmage electoral area.
A Fianna Fail source said that if Mr Mulcahy failed to win, it would be for two reasons: firstly, Dr Upton will benefit from a huge sympathy vote and, secondly, the traditionally bad fortunes of governments in by-elections.
However, the reality is that Fianna Fail is unlikely to have the figures. In June 1997 it received 34.4 per cent of the vote, returning two deputies, Mr Ben Briscoe and Mr Sean Ardagh, but the same share of the vote in the by-election would not be enough for Mr Mulcahy to win, due to the strength of the combined Labour/Fine Gael vote.
In 1997 Pat Upton polled 10.4 per cent of the first-preference vote. Mr Byrne received 11.3 per cent for the then DL, but did not get enough later preferences to be elected. Fine Gael's Mr Gay Mitchell topped the poll with 25 per cent. With Dr Upton expected to poll ahead of the Fine Gael candidate, she will benefit from the party's transfers.
Fianna Fail is insisting that the Ansbacher controversy, revelations in the tribunals and the issue of the Taoiseach signing blank cheques for Mr Haughey's party leader's account will not be negative factors, but privately the party is bracing itself for attack.
The Fine Gael candidate, Ms Catherine Byrne, was recently elected for the first time to Dublin Corporation for the south inner city area. A community worker for 20 years, she is personable and popular on the doorsteps but will not make up enough ground to win the seat.
With three major hospitals in the constituency, Mr Mulcahy can expect to feel the heat if the nurses strike goes ahead.
Housing and traffic are also big issues. Former local authority houses are now making more than £100,000 in some of the working-class areas where houses could not be sold a few years ago. Sons and daughters of families settled in the constituency for years cannot afford to buy homes there.
The Progressive Democrats are not fielding a candidate. Mr Aengus O Snodaigh (35), a Bord na Gaeilge employee, is representing Sinn Fein, and promises to tackle the drugs problem.
Trinity College librarian Mr John Goodwillie is running for the Green Party while Mr Shay Kelly from Crumlin, a Dublin Corporation employee, is representing the Workers Party.