Fianna Fáil faces a tough battle to retain its only seat in the three-seater constituency of Kildare North.
Leixlip solicitor Mr Paul Kelly, who narrowly missed out on a seat in the 2002 general election, is favourite to receive the party nomination.
While it is unusual for a Government to win a by-election, party sources point out that north Kildare was one of the few areas where Fianna Fáil held onto its seats in June's local elections.
Mr Kelly polled more than 5,000 votes in 2002, just several hundred votes behind Fine Gael's Bernard Durkan TD, who took the final seat. Labour's Emmet Stagg took the second seat, while Minister McCreevy topped the poll.
The Leixlip solicitor, however, is likely to face strong competition for the Fianna Fáil nomination. Other contenders include Mr McCreevy's personal assistant, Cllr Michael Fitzpatrick. Cllr Liam Doyle from Kilcock and Cllr Willie Callaghan from Naas may also seek the nomination.
Fianna Fáil is likely to face a strong challenge from Fine Gael and Labour, while the prospect of Independent councillor Catherine Murphy, standing also adds an unknown quantity to the race.
Ms Murphy, a former Labour and Democratic Left candidate, polled more than Mr Kelly in his Leixlip base in last month's local elections. Given that she did not run in the last election, local observers say it is hard to gauge what threat she poses.
Fine Gael, with four councillors in the area, has a number of strong contenders who include barrister Katie Ridge, daughter of former TD Therese Ridge.
Cllr Brendan Weld from Clane, Cllr Senan Griffin, a primary school teacher from Maynooth, and Cllr Billy Hillis from Naas are also potential contenders.
Cllr John McGinley, a worker-director with ESB, is likely to be a front-runner for the Labour Party nomination. Cllr Kevin Byrne from Straffan, and Cllr Paddy McNamara from Naas, are other possible contenders
Senator Kate Walsh, who polled just over 11 per cent in the 2002 general election, is likely to stand for the PDs.
