Alasdair McDonnell facing Sinn Fein's slick electoral machine in South Belfast
Noel McAdam evaluates the battle for South Belfast
South Belfast is a very tough constituency to call. The failure of the DUP and Ulster Unionists to include the area in their electoral pact - and decision of Sinn Fein to run a candidate this time - renders an already fairly fluid mix even more unpredictable.
But if the unionist vote divides fairly equally, sitting MP Alasdair McDonnell has a good chance of survival. Traditionally a unionist citadel where the Rev Martin Smyth carried all before him for 22 years, the nationalist SDLP leader McDonnell has held the seat since 2005.
But this time he faces the slick Sinn Fein electoral machine and a top-drawer candidate in former Lord Mayor Mairtin O Muilleoir.
McDonnell, a GP, and O Muilleoir, a writer and businessman, are good performers on the doorsteps, but the Sinn Fein man has the added advantage of a prolific presence on social media. It is a stand-off which also leaves McDonnell more dependent on tactical votes.
Against that, however, South Belfast has a more middle-class population in economic terms, with 37% of working age adults engaged in professional or managerial occupations, which should operate in the SDLP's favour.
McDonnell has the incumbency factor in his favour and remains favourite to hold the seat.
On the unionist side, the battle is between current Junior Minister Jonathan Bell for the DUP, who represents Strangford in the constituency, and Rodney McCune, a young barrister, in the UUP corner. Protracted talks between their two parties delayed McCune's entry into the fray - Bell was announced weeks earlier - but he and his team have been making up for lost time.
McCune is on the liberal wing of the UUP and should therefore be fighting for some of the same voters as Paula Bradshaw, who defected from the UUP in 2010 to Alliance, which has improved its performance in every election in the constituency since 2003.
So the second most likely scenario would see Bell come through the middle, in a situation where O Muilleoir had muted McDonnell with a strong performance and McCune did poorly.
Ukip's Bob Stoker is a rank outsider but will use the result to assess the prospects for joining its sole MLA David McNarry in next year's Assembly election. The Belfast Telegraph's polling partner LucidTalk's latest results gave McDonnell a 65% rating for holding the seat, which is viewed as being "fairly marginal", with the prospect of Bell ringing up a victory dropping by 5%.