The Irish News is this morning reporting that Sinn Féin and the SDLP have held talks at Stormont in the context of a possible electoral pact. This is something that Sinn Féin have canvassed at previous elections. In 2010, SF unilaterally stood down in favour of the SDLP in South Belfast. The SDLP held the seat, and Sinn Féin was able to squeeze the SDLP vote in Fermanagh & South Tyrone, winning by 4 votes. There were no such moves in 2015, when Sinn Fein lost Fermanagh & South Tyrone and the SDLP barely held on in South Belfast.
The SDLP has traditionally opposed pacts but the threat to South Belfast may be concentrating minds, as well as the threat to its other two seats, Foyle and South Down, where it was outpolled by Sinn Féin in this year's assembly election.
The existence of an anti-Brexit majority in Northern Ireland also creates the opportunity to cast any pact in non-sectarian progressive terms, although the Irish News report suggests that active participation by non-nationalist parties will be limited, there could be unilateral withdrawals in their favour. It might also be worthwhile for nationalist parties to consider stating that they will not use the result of this Westminster election as a mandate for a border poll, but rather to assert Northern Ireland's special circumstances in relation to the EU.
A progressive pact could affect the result in a number of seats, including Fermanagh and South Tyrone, South Belfast, East Belfast, Upper Bann and North Down. It might draw in a number of nationalist seats where the pro-Brexit threat is more notional but anti-Brexit feeling is very strong.
The dilemma for potential participants is whether the opportunity to reassert the strong anti-Brexit mandate from the referendum in Northern Ireland outweighs the likely effect of cannibalising their overall vote ahead of what could still conceivably be the third Assembly election in two years. Part of the reason that a unionist pact is likely now, is the lock-in effect of having to defend seats won with past pacts. The resulting effect on vote-share may have contributed to unionist losses in the Assembly elections, which reflect overall shares much more closely than those to Westminster.
With that caveat, here's a look at how a pact could play out in individual seats.
A progressive pact here would likely imply Sinn Féin and SDLP standing down in favour of Alliance. Alliance is unlikely to reciprocate and might not see nationalist support in unionist East Belfast as an unmixed blessing. Nevertheless, the move would be essential if a pact were to be seen as progressive rather than simply nationalist.
Alliance has a chance of regaining this seat with Naomi Long as candidate.
A pact here might give Sinn Fein a free run against Nigel Dodds of the DUP. The nationalist divide is, however, deeper in Belfast than in more rural seats, and Gerry Kelly might not be well-placed to hoover up all SDLP votes.
Dodds built up a significant lead in 2015 thanks to a unionist pact, but the electoral danger to him would be real.
The logic of a pact here might see Sinn Féin standing down in favour of the SDLP as they did in 2010. The Green Party have said they will consider arrangements with parties that take their seats, which might be relevant here, if anywhere. A Green withdrawal would be a significant signal if Alliance refused to play a role. Its difficult to see a quid pro quo for this, although the Greens might benefit in vote-share from nationalists standing down in North Down.
A pact here might make it significantly easier for the SDLP to hold the seat.
As a safe Sinn Féin seat, there is little logic to a pact here, unless, it is a quid pro quo to focus resources somewhere else. Indeed, a pact might actually benefit pro-Brexit People Before Profit.
A safe unionist seat. It's questionable whether a single nationalist candidate or withdrawal in favour of Alliance would produce a result that justifies the loss in vote-share.
A decade ago this might have been the place to give the SDLP a target. As it is Sinn Féin is the largest anti-Brexit party, but Gregory Campbell might still be just out of reach of any conceivable progressive coalition. Update: Independent unionist Claire Sugden has been suggested as an anti-Brexit candidate here.
Fermanagh & South Tyrone
A unionist pact barely won this seat from Sinn Féin in 2015. Winning this border constituency back would be a key goal for the party in an anti-Brexit pact, and it may do it anyway given the political tide seen in the 2017 Assembly election.
The threat to the SDLP here is from Sinn Féin and not the pro-Brexit DUP, but a deal here in the wake of Sinn Féin's strong assembly result might be one of the attractions of a pact to the SDLP.
A safe unionist seat with alliance the strongest of the anti-Brexit parties. Arguably not competitive enough to justify a pact that might weaken participants overall vote shares in a future assembly election.
Sinn Féin has seen off unionist pacts here without help from the SDLP, but a unionist pact involving the DUP might still draw this seat into any negotiations.
Newry & Armagh
A unionist pact cut Sinn Fein's majority in half in 2015, so this seat could come into play in negotiations with the SDLP.
Ian Paisley Jr is probably beyond the reach of any progressive candidate here.
As a seat held by an anti-Brexit unionist, the approach taken to this seat would be a key test of the anti-Brexit nature of any progressive pact. Sinn Féin has just started to make a serious effort here for the Assembly, with little prospect of short-term reward. The question of long-term growth v. progressive hegemony is perhaps the key to the prospects for a pact.
Danny Kinahane's pre-referendum opposition to Brexit makes a progressive pact hard to justify on anti-Brexit grounds, unless there is a unionist pact involving the DUP, which there may well be. The seat would likely remain unionist in either scenario.
The prospect of a unionist pact involving the DUP might also create grounds for a progressive pact, the bigger threat to the SDLP here is from Sinn Féin and has been seen off in the past with tactical unionist votes. A progressive pact would be a significant shift in strategy, but anti-Brexit feeling might create the grounds for it.
As with Lagan Valley and South Antrim, this DUP seat is arguably not competitive enough to make a pact worthwhile.
The DUP's tenure in this seat would arguably justify a progressive pact here, especially as the DUP's lead over Sinn Féin was less than the SDLP's total vote. However, a likely unionist pact would put the seat beyond reach.
This is a safe Sinn Féin seat, although a unionist pact might make it competitive enough to justify a progressive response.