A by-election will be held to elect a TD to replace former Fianna Fail Minister Seamus Brennan.
Mr Brennan held his seat in Dublin South at every general election since 1981, often topping the poll and occasionally being among the highest vote-getters in the capital.
Taoiseach Brian Cowen will decide when to hold the by-election as Mr Brennan was a Fianna Fail TD, but it's likely to be held later in the year.
There is no specific legal requirement on when to hold the by-election, but it is generally held within six months.
Following Mr Brennan's death yesterday, there was immediate speculation about the candidates for the by-election. Despite the old adage that governments don't win by-elections, Fianna Fail would be the favourites to hold the seat, particularly if one of Mr Brennan's children wants to run.
Fianna Fail will have to approach this issue sensitively over the summer months. In the absence of a member of the Brennan family, Fianna Fail's candidate would most likely be Senator Maria Corrigan or else local councillor John Lahart.
Although she has been a candidate in the past two elections and is already in the Oireachtas, Senator Corrigan's relationship with Bertie Ahern's friend Joe Burke may attract some controversy.
Fine Gael's candidate will probably be Cllr Jim O'Leary, who ran in the general election, but a high-profile parachute candidate cannot be ruled out. FG already has two TDs in the constituency, Olivia Mitchell and Alan Shatter, and a good by-election performance will be important for Enda Kenny.
Labour Party Senator Alex White also ran in the general election and is favoured by party headquarters. But Dublin South is not a Labour Party hot bed.
PD Senator Fiona O'Malley may also be a candidate as she has decided to contest this constituency at the next general election.