The TUV plan was set out clearly by Jim Allister on 14 November:
"It is by a sufficient number of MLAs refusing to operate mandatory coalition that it will be starved of its legitimacy and all those who claim opposition to mandatory coalition will be tested. Then, we will see the durability of mandatory coalition. I believe it will flounder and the inevitable outcome will be fresh negotiations within which a sizeable section of Unionism will not be rolling over. Once mandatory coalition is made inoperative then alternatives will kick in, because the present Stormont parties’ reliance on sustaining an Assembly is such that even those who presently declare otherwise will then accept the logic of voluntary coalition."
When Allister talks of the 'legitimacy' of the 'mandatory coalition' it is likely that he is talking about its 'legitimacy' amongst unionists only. Although he does not say it clearly, it is evident from other sources that this unionist legitimacy derives in large part from the existence of a unionist First Minister.
In order for unionism to lose the First Minister post, under the terms of the Northern Ireland (St Andrews Agreement) Act 2006, if after an election to the Assembly 'the party which is the largest political party of the largest political designation is not the largest political party, any nomination to [the post of First Minister] shall instead be made by the nominating officer of the largest political party'.
So, in order for the Executive to lose its unionist legitimacy, Allister believes, his party needs simply to reduce the number of DUP seats to less than the number of Sinn Féin seats.
At present there are 36 DUP MLAs against 28 Sinn Féin MLAs. His aim is to capture at least nine DUP seats, or cause them to be lost, bringing their total to 27 or less. If UCUNF take another couple of DUP scalps then that just makes the Sinn Féin position even stronger. A resurgent SDLP does not feature in Allister's thinking, probably correctly.
Can the TUV take one quarter of the DUP's seats? So far, on the few occasions when the parties have gone head-to-head the TUV has taken around 40% of their combined vote. But these occasions are quite specific, and have involved no more than two TUV candidates – Allister himself, and Keith Harbinson in Dromore. Apart from them, the TUV has few recognisable or electable faces. Nonetheless, the TUV may well be the inheritor of the unionist tradition of voting for a donkey if it has a union jack wrapped around it, so the quality of its candidates may not matter.
In order to take nine DUP Assembly seats the TUV need to pick up one per constituency, on average, or to split the unionist vote sufficiently that fewer unionists of any stripe are elected.
As things look at the present, such a scenario is possible. The TUV itself could, on a good day, pick up at least seven DUP seats (one each in East and North Belfast, East and North Antrim, East Derry, Lagan Valley and Strangford), while another seat could fall to the UUP (Fermanagh and South Tyrone), and two to nationalists (Foyle and Newry and Armagh). This would leave the party strengths (ceteris paribus) at: DUP 26, UUP 19, TUV 7, PUP 1 versus Sinn Féin 29, SDLP 17, and Alliance/others at 9. Sinn Féin as largest party would nominate the First Minister, and, in Allister's plan, the unionists would walk out en bloc.
Allister's plan requires the DUP to refuse to nominate for the Deputy First Minister post – and on this he is probably right. But it then requires Sinn Féin to "accept the logic of voluntary coalition" and rule themselves out of power until such time as unionists decide they are sufficiently 'house-trained' (i.e. never, as Allister himself believes ("TUV will never enter government with Sinn Fein"). This is where Allister's plan starts to part company with common sense.
The Westminster elections next year will act as a dry run for the TUV. Since the constituencies are the same for Westminster and the Assembly, the party's performance next year will allow an accurate prediction of its prospects in 2011 to be made. If the TUV does well in 2010, then the planning for what to do in 2011 when the Executive collapses can already begin. If the TUV do badly in 2010, then the Executive may stagger on until its next crisis.