None of Northern Ireland's 18 seats at Westminster are represented by the mainland parties. The Ulster Unionists once took the Conservative whip but pulled out of their alliance in 1974 in protest at the Sunningdale Agreement. SDLP MPs sit with Labour in the House of Commons. Currently, Northern Ireland is represented by ten Democratic Unionists (DUP), seven Sinn Fein and one independent. Sinn Fein follow a policy of abstentionism and do not take their seats at Westminster.
Since 2015, Northern Ireland has had two elections to its devolved assembly at Stormont. The first was held in 2016 and saw the Democratic Unionist Party remain the largest party with 38 MLAs. Martin McGuiness resigned from his role as Deputy First Minister on 9th January 2017 in response to the Renewable Heat Incentive scandal. The power sharing executive then collapsed as Sinn Fein refused to nominate a replacement Deputy First Minister. A snap-election to Stormont was then called and the Democratic Unionist Party lost five seats. Sinn Fein's vote share increased by a healthy 3.9 percent and the party finished one seat behind the DUP on 27. Since the snap election, talks between the DUP and Sinn Fein have broken down and no new executive has been formed.
In 2017, the Democratic Unionists will be looking to take Belfast South from the SDLP where they require a relatively 1.16 percent swing to take the seat. The only other seat where the DUP could be competitive is Antrim South, held by the Ulster Unionists, an achievable swing of 1.2 percent is required to take the seat. The UUP suffered a poor result at the most recent assembly election will be looking to hold their two existing seats and take Upper Bahn from the DUP on a 2.4 percent swing. Newry and Armagh, currently held by Sinn Fein, is also competitive for the UUP but still requires a 4.19 swing to take the seat.
North Down is currently held by Sylvia Hermon, a former Ulster Unionist, turned independent. She comfortably held the seat in 2015 and pending any major changes, she is likely to hold it again.
For Sinn Fein, they will be looking to target Fermanagh and South Tyrone, a seat which they lost to the Ulster Unionists in 2015. With a majority of 1.04 percent, this is the most marginal Northern Irish seat. Upper Bann and Belfast North, both currently held by the DUP, are likely to be targeted by Sinn Fein. The other three seats which could be targeted by Sinn Fein are Down South, Foyle and Belfast. All three have majorities of less than 10 percent over Sinn Fein and are currently held by the SDLP. In Belfast South, Sinn Fein finished fourth in 2015. The SDLP will find it very difficult to gain any additional seats this time round as the smallest swing which they require is 8.59 percent in Newry and Armagh where they are in third place behind the Ulster Unionists and Sinn Fein.
It will be interesting to see if the Ulster Unionists and Democratic Unionist Party form an electoral alliance for this election, as they did in six seats in 2015. Following the loss of the unionist majority at Stormont earlier in the year, this could be more likely. Given Northern Ireland's vote to remain in the European Union, it may be worth watching some of the seats currently held by the pro-brexit DUP and whether or not this has any effect on the results. If the Conservatives contest any constituencies in Northern Ireland, as they are expected to do, their vote share will be worth looking at.