Now, it is not improbable (though I think unlikely) that Sinn Féin will be the largest party in terms of votes in next tear's election. They topped the poll in both 2009 (for the European Parliament) and 2010 (for the Westminster election) as follows:
| European election 2009 | Westminster election 2010 | ||
| Sinn Féin | 126,184 (26%) | Sinn Féin | 171,942 (25.5%) |
| DUP | 88,346 (18.2%) | DUP | 168,216 (25%) |
| UUP/Conservatives | 82,893 (17.1%) | SDLP | 110,970 (16.5%) |
| SDLP | 78,489 (16.2%) | UUP/Conservatives | 102,631 (15.2%) |
| TUV | 66,197 (13.7%) | Alliance | 42,762 (6.3%) |
| Alliance | 26,699 (5.5%) | TUV | 26,300 (3.9%) |
| Green Party | 15,764 (3.3%) | Ind U's | 43,743 (6.5%) |
| Others | 7,577 (1%) | ||
SF's position at the top of the table in both elections was essentially achieved not so much by their own merits but by the DUP shedding support to the TUV in the European election, and by its support of independent candidates in two otherwise promising constituencies, North Down and Fermanagh-South Tyrone. Had the DUP contested either constituency in May, they would certainly have gained more than the 3700 votes necessary to top the right-hand side of this table.
It is worth pointing out, of course, that Assembly elections have often tended to provoke fragmentation among Unionists; that the TUV had a poor Westminster election but may have a better Assembly election; and that SF may be able to squeeze the SDLP still further than they have already done next May. But my own gut feeling is that any fragmentation will be more than compensated for by the return to party voting in North Down and FST; that the TUV are a busted flush; and that SF's vote in 2009 and 2010, though impressive, was actually down from its historic high of 26.2% in the 2007 Assembly election. Other things being equal (normalement, as we say in Belgium) I therefore expect the DUP to return to the top spot next year.
In any case, it doesn't matter much to the appointment of the heads of the government. The St Andrew Agreement, paragraph 9, has this to say about the appointment of the First Minister and Deputy First Minister:
The Nominating Officer of the largest party in the largest designation in the Assembly shall make a nomination to the Assembly Presiding Officer for the post of First Minister. The Nominating Officer of the largest party in the second largest designation in the Assembly shall similarly nominate for the post of Deputy First Minister.This is translated into the legislation (section 8.1 of the Northern Ireland (St Andrews Agreement) Act 2006, which inserts a new Section 16A into the Northern Ireland Act 1998, if you are interested) as follows:
(4) The nominating officer of the largest political party of the largest political designation shall nominate a member of the Assembly to be the First Minister.So in fact, if SF end up with 32 seats to the DUP's 30, it doesn't matter because if Unionist MLAs still outnumber Nationalist MLAs, the leader of the largest Unionist party in the Assembly still gets the top job.
(5) The nominating officer of the largest political party of the second largest political designation shall nominate a member of the Assembly to be the deputy First Minister.
The balance of Unionist v Nationalist MLAs in the Assembly has varied over the years as follows:
So, to pass the combined total of Unionist seats, Nationalists must make a net gain of six seats from Unionists in next year's election, which is twice as many as the net advance of three which they made between 2003 and 2007 (and more than twice the net change from 1998 to 2007). I can see a couple coming out of the new boundaries, if the everything goes right for Nationalist parties, but I don't see it being anywhere near enough to activate Section 16A.4 of the revised Northern Ireland Act on behalf of Martin McGuinness, or of any Nationalist politician, for some time to come.
1998 2003 2007 Unionists 58 59 55 Nationalists 42 42 44 Others 8 7 9
Which makes me wonder what all the fuss has been about.
Edited to add: As Conal points out in comments, I have got this wrong. He draws my attention to the new Section 16C.6 of the 1998 Act as amended by Section 8 of the 2006 Act:
If at any time the party which is the largest political party of the largest political designation is not the largest political party—Which is pretty definitive that if SF get more seats than the DUP then Martin McGuinness gets to be First Minister.(a) any nomination to be made at that time under section 16A(4) or 16B(4) shall instead be made by the nominating officer of the largest political party;
I still don't think it's likely. SF could gain four seats on 2007 if the everything goes right (in FST, Upper Bann, Mid Ulster and East Antrim) but are pretty certain to lose one in Lagan Valley. But even if the DUP lose their most vulnerable seats (in Strangford, East Belfast, East Londonderry and South Down) they will still end up a tick ahead, 32 to 31. However I admit that it is a little less improbable than I had first thought.