The SDLP could see its majorities in three Westminster constituencies cut under Boundary Commission recommendations proposed today.
The commission has suggested retaining Northern Ireland's 18 constituencies but changing the boundaries in 12, with the SDLP losing parts of its leader Mark Durkan's constituency in Foyle to East Derry and also parts of Eddie McGrady's stronghold in South Down to Strangford.
SDLP strategists were concerned today that if the recommendations are implemented additions to deputy leader Dr Alasdair McDonnell's South Belfast constituency could boost unionist hopes of taking back the seat.
The recommendations will be reconsidered once Stormont Environment Minister Arlene Foster publishes her plan for the future shape of local government in the North.
However, the commission said it believed in advance of her proposals it should not delay its submission to Northern Ireland Secretary Shaun Woodward. "Once new ward boundaries are established the commission propose to consider whether, exceptionally, to conduct an interim review of constituencies," it said.
Under the proposals, the boundaries of Belfast's four constituencies will all change. DUP deputy leader Peter Robinson could tighten his grip on East Belfast by gaining Dundonald and other Castlereagh wards from his wife Iris's Strangford constituency.
Mr Robinson's DUP colleague the North Belfast MP Nigel Dodds will see his constituency take Glengormley, Glebe and Hightown away from South Antrim.
Sinn Féin president Gerry Adams' hold on West Belfast could be strengthened if recommendations to absorb Derryaghy and Dunmurry are implemented. The party believe this may also boost the party's chances of holding five of the six Assembly seats.
However the move could weaken Sinn Féin Lagan Valley MLA Paul Butler's chances of retaining his Stormont seat.
While SDLP strategists believe they could gain votes in South Belfast with the inclusion of Carryduff East and West, they were disappointed Dunmurry had not been returned to the constituency and felt unionists will gain more with the inclusion of other Castlereagh Council wards.
Nationalist hopes of a third Assembly seat in East Derry will be boosted by the inclusion of Claudy and Banagher from the Foyle constituency - although it is believed that would eat into Mr Durkan's Westminster majority.
DUP First Minister Ian Paisley's North Antrim constituency would lose three local government wards in the Glens of Antrim, putting Declan O'Loan of the SDLP's seat under pressure. However the transfer of the Glendun, Glenariff and Glenaan wards to East Antrim could boost SDLP hopes of gaining a seat.