Why is today the de facto deadline for political agreement? Mr David Trimble resigned as First Minister on July 1st. Under the Northern Ireland Act 1998, a new election for the posts of First and Deputy First Minister must be held in the Assembly within six weeks.
That six-week period elapses on Sunday so the Assembly would need to meet on Saturday. The Assembly would be recalled by the Speaker, Lord Alderdice. Although there are no legal requirements, protocol would mean members receiving at least 24 hours' advance notice, especially during a holiday period when many might have to travel long distances to return to Belfast. Postal or telephone communication to members would have to take place today.
If there is a last-minute deal, is it certain that Mr Trimble and Mr Seamus Mallon will be returned to their posts?
Absolutely not. Even if, at the eleventh hour, Mr Trimble receives enough reassurances on decommissioning from the IRA to encourage him to return to government with Sinn Fein, he will face serious problems being reelected First Minister.
Any agreement he makes with Sinn Fein and the governments might well receive the support of the vast majority of his Assembly party but it takes only one or two dissidents to scupper his plans.
Candidates for First and Deputy Minister require the support of both a majority of nationalists and a majority of unionists in the Assembly. The latter is not guaranteed. The 21 DUP Assembly members, and seven other members belonging to smaller unionist parties, combine to make a 28strong anti-agreement bloc.
Mr Trimble would be relying on the support of the Assembly's 28 UUP members, including Mr Peter Weir who is vociferously anti-agreement, and the two Progressive Unionist Party members. It is highly unlikely Mr Weir would vote for Mr Trimble. The support of three other anti-agreement UUP Assembly members is also questionable.
Several UUP Assembly members have also expressed objections to voting for Mr Seamus Mallon given his refusal to support the North's new police force.
If Sunday passes without the re-election of the First and Deputy First Ministers, who decides what happens next?
The Northern Secretary, Dr John Reid, has two basic options. The first is to suspend the Assembly by signing a suspension order under Section 4 of the Northern Ireland Act 2000.
His second option is to dissolve the Assembly and call fresh elections under Section 32 of the Northern Ireland Act 1998.
If the British government decides on fresh elections, Dr Reid at some point would have to sign an order dissolving the Assembly and calling fresh elections.
There is no legal requirement for Dr Reid to act immediately. However, he is likely to act within "a reasonable period", according to British government sources, otherwise the process would lose credibility.
Although the date of the poll is Dr Reid's choice, he can consult with the parties. The most likely date would be late September or October. In the meantime, the Executive would stay in operation.
However, observers believe Dr Reid is unlikely to call fresh elections. The DUP and Sinn Fein made massive gains in June's Westminster poll and could well make even further advances in the autumn. Fresh elections could leave the DUP and Sinn Fein as the largest parties in the Assembly, making them eligible to hold the posts of First and Deputy First Ministers. This would be unworkable.
So is Dr Reid likely to suspend the Assembly and the other political institutions?
The British government is loath to do so because the institutions would lose considerable credibility. Nationalists oppose suspension, which they see as the British government allowing unionists to hold the entire political process to ransom.
However, suspension still probably remains a lesser evil for the British government than elections.
How long could the Assembly be suspended for?
Dr Reid could opt for an open-ended suspension, which allows the parties a non-time-limited period to work out a new deal. In theory, the Assembly could be suspended for 10 weeks or 10 years.
During this period, all devolved powers would revert to Westminster. Assembly members would remain in office but the Assembly would not meet or carry out any functions.
Is a shorter suspension period possible to prevent the institutions losing credibility?
Yes. Dr Reid can suspend the Assembly under Section 4 of the Northern Ireland Act 2,000 and then restore it the next day, or a few days or weeks later.
The advantage is that when the Assembly is restored, the situation reverts to what it was when Mr Trimble resigned as First Minister on July 1st, with another six-week period coming into operation for the parties to hammer out a deal.
Intense negotiations between the two governments and the proagreement parties would be likely during this period. There would also be renewed pressure on the IRA to move further on decommissioning. Although Executive meetings would not take place, it is understood the 11 ministers, excluding Mr Trimble, would be able to continue working.
What happens if a deal is reached at the end of the six weeks?
The same scenario prevails as if a deal is reached now - Mr Trimble and Mr Mallon will still have to face re-election in the Assembly as First and Deputy Ministers.
What happens if a deal is not reached after six weeks?
Dr Reid can suspend the Assembly and restore it again, with a new six-week period coming into operation during which a deal could be reached. But he would be unlikely to do so as repeated suspension would lead to a major loss of credibility in the institutions. He would be most likely to suspend the Assembly indefinitely or order fresh elections.