The Dáil may adjourn to allow parties more time to form a new government, writes Stephen Collins
If the Dáil fails to elect a taoiseach next Thursday, Mr Ahern will have to formally resign from office and continue in an acting capacity.
The Dáil will then be adjourned for as long as necessary to give all the parties time to negotiate the formation of a government that can command a majority.
The procedure is that Taoiseach Bertie Ahern would go to Áras an Uachtaráin and hand in a formal note of resignation to President Mary McAleese and he would then return to the Dáil and announce an adjournment until an agreed date.
Mr Ahern would continue to carry out his functions and would attend the important EU summit a week later as the acting head of the Irish Government.
All of the Government Ministers would also continue to serve in an acting capacity, with the exception of Minister for Justice, Michael McDowell, who has not been elected to the 30th Dáil.
The acting taoiseach would allocate the responsibility for that department to another minister, most likely himself. The President has no role in the formation of government which is purely a matter for the Dáil under the terms of the Constitution.
The issue did not come to a head until 50 years after the Constitution was enacted when the Dáil failed to elect a taoiseach following a general election.
It happened when Charles Haughey and Fianna Fáil failed to win an expected overall majority. When the 26th Dáil met on June 29th, 1989, it failed to elect a taoiseach when Mr Haughey, Fine Gael leader Alan Dukes and Labour leader Dick Spring, were proposed in turn and defeated by ever bigger margins.
It was the first time in the history of the State that the Dáil did not elect a taoiseach in the aftermath of an election and the country entered uncharted constitutional waters.
Mr Haughey initially refused to resign the office of taoiseach, despite his Dáil defeat.
He had been advised by his attorney general, John Murray, (the current Chief Justice) that he would not be required to do so and for a time he tried to stick to that position, despite the strong objections of Mr Spring.
Ultimately he bowed to the storm and agreed to go to Áras an Uachtaráin, where he handed in a written note of resignation to then president Patrick Hillery.
Mr Haughey and his ministers then continued in office in an acting capacity.
The defeat prompted Fianna Fáil to abandon what it used to call a "core value" and it entered the negotiations that led to the first coalition with the PDs.
The Dáil was initially adjourned for a week and then adjourned twice again before the talks came to a successful conclusion. It was not until July 12th that a government was finally put in place on the fourth occasion that the Dáil met after an election.
A similar situation developed after the 1992 general election which saw Fianna Fáil's share of seats drop to 68 under Albert Reynolds after the break up of the coalition with the PDs.
Again the Dáil met and failed to elect a taoiseach but this time around it was taken as a matter of course. Negotiations on a programme for government between Fianna Fáil and Labour again involved Bertie Ahern, and again they dragged on as both sides tested each other out.
It was not until the Dáil met for the third time on January 12th, 1993, that Albert Reynolds was elected taoiseach with the biggest majority in the history of the State and the ill-fated first and only Fianna Fáil-Labour coalition began its life.