BERTIE AHERN will be re-elected taoiseach next Thursday, that much seems certain. But the composition of his government is still very much in doubt.

While there has been increased speculation about a 1989-mark II scenario, with the D�il failing to elect anybody as taoiseach, that ignores the simple arithmetic which points to only one outcome.

Fianna F�il has 78 votes, and given that the PDs are currently negotiating a programme for government with their coalition partner of the past 10 years, take it as read that their two votes will be cast in favour of Ahern for taoiseach.

Four independents also seem certain to vote for Bertie Ahern - the two FFgene pool deputies, Jackie Healy-Rae and Beverley Flynn, along with Michael Lowry and Finian McGrath. The belief is that deals will have been agreed with all four deputies by Tuesday morning.

That gives Ahern a total of 84 votes, sufficient to return him to power.

But it is apparent this weekend that his clear preference remains a government made up of four legs - FF, the Greens, PDs and the Independents. While those hopes seemed to be jettisoned on Friday evening when the Greens withdrew from talks, there is still a cautious confidence within high levels of Fianna F�il that a deal can still be put back together.

Informal contacts have been made between the two sides this weekend and it is believed that there has already been contact between the taoiseach and Green Party leader Trevor Sargent. Further contact between the two men is likely sooner rather than later in an attempt to bridge the gap between the two sides.

The belief in Fianna F�il is that some movement is possible on each of the bigticket issues identified by Sargent at Friday's Green press conference - climate change, transport, education funding, local government reform and health.

Serious work is being done this weekend by Fianna F�il to come up with ways of trying to lessen what Sargent described as the "serious blockages" on these areas.

But what Fianna F�il cannot know is if that movement will be enough to satisfy the Greens.

There is no question that Green Party figures remain open to the possibility of resuming negotiations but it is also clear that they will not bring a coalition deal to their party convention unless they can sell it as a "new government" with a green tinge.

The key to a successful outcome between the two parties may well lie in Fianna F�il convincing the Greens to accept that they need to prioritise two or three of those big-ticket items, with Fianna F�il giving some serious ground on those issues. The problem is that, given that the two parties have never negotiated with each other before, nobody is sure whether this is possible. Presumably, the talks between Ahern and Sargent, if and when they happen, will be crucial in this regard.

One possible logistical problem to a government including the Greens, even if a deal is reached between the two sides by tomorrow, (now seen as the deadline for any agreement) is the smaller party's requirement to put that deal to a party convention. While the belief is that the Green leadership could deliver the required two-thirds majority, if the party sticks to its insistence that the convention has to be held on a Saturday or Sunday, it rules out a deal being endorsed before Thursday's D�il vote.

However, it's hard to imagine the Greens excluding themselves from government on the basis that they couldn't hold a convention on Tuesday or Wednesday night.

The logistical difficulties shouldn't be underestimated, but they surely can be overcome.

But in the event of Ahern and Sargent being unable to bridge the gap between the two parties, Fianna F�il can still be supremely confident that Ahern will win Thursday's vote for taoiseach. The first vote on Thursday will be for ceann comhairle, and without the Greens on board, Fianna F�il will be looking to give that job to an opposition deputy to reduce the number of deputies who can potentially vote against Bertie Ahern for taoiseach. Labour's Ruairi Quinn and Brian O'Shea are the two names being spoken of.

However, if the Greens are on board - giving Ahern a likely 90 votes in the D�il - the highly sought-after position will remain within Fianna F�il, with S�amus Kirk of Louth being mentioned as a possible candidate.

It will then come to the nominations for the position of taoiseach and it is clear that Bertie Ahern still holds all the advantages.

There are the aforementioned likely 84 votes that he should be able to muster - enough on their own to elect him taoiseach - but it is very possible that Sinn F�in will abstain when it comes to the vote on Ahern.

The party did vote against Ahern in 2002 but, with Fianna F�il and the PDs having 89 seats between them, the outcome was never in doubt. In 1997, when the numbers for taoiseach were very tight - FF and the PDs had a total of 81 votes - Caoimhgh�n � Caol�in voted for Ahern.

Talk that Ahern may fail to get the necessary votes and that Enda Kenny may then be in a position to put together a coalition remains fanciful. Even accepting the highly implausible scenario that the PDs might vote for him, for Enda Kenny to be taoiseach, he would need either the votes of Sinn F�in or of Beverley Flynn and Jackie Healy-Rae.

A lot of changes have taken place since the Republican movement first embraced the peace process, but not enough for Sinn F�in to vote for a Fine Gael taoiseach or for Fine Gael to accept the votes of Sinn F�in. The notion that Flynn or Healy-Rae would favour Kenny over Ahern is also simply not credible.

There has been renewed speculation about a Fianna F�il-Labour deal, but Labour is tied in to voting for Enda Kenny for taoiseach on Thursday and, by the time it is free to explore other options, Ahern will be on his way to �ras an Uachtar�in with his new cabinet.

So Thursday will, yet again, be Bertie Ahern's day - the next 48 hours will determine if it is a part of an historic new partnership with the Greens or simply history repeating itself with a third successive term for Fianna F�il and the PDs.