Sinn Fein has pulled out of the race for a General Election constituency in a surprise bid to clear the way for its nationalist rivals, the SDLP.
The move came after party president Gerry Adams asked the SDLP to enter a pact in two seats to match a similar agreement between the Democratic Unionists, Ulster Unionists and Conservatives.
Republicans had asked the SDLP to step down in Fermanagh-South Tyrone in exchange for Sinn Fein withdrawing in South Belfast in a bid to safely defend the seats held by the two parties, but the SDLP said all such pacts were sectarian and rejected the plan.
Sinn Fein president Gerry Adams said today his party would nevertheless withdraw in South Belfast.
Mr Adams said: "Sinn Fein South Belfast candidate Alex Maskey today withdrew his nomination for the forthcoming Westminster election.
"The Sinn Fein decision to maximise nationalist representation comes after a unionist unity candidate was put forward in Fermanagh and South Tyrone and the SDLP rebuffed earlier discussions on an electoral pact.
"This Sinn Fein initiative is aimed at protecting the two nationalist seats under threat from unionism."
Mr Adams was in Enniskillen today at the heart of the Lakeland constituency where his colleague Michelle Gildernew risks losing her seat to the effective joint-unionist candidate Rodney Connor, who will stand as an independent.
The Conservative Party has been criticised for backing the "unionist-unity" candidate having declared it would not engage in contests that risked becoming so-called sectarian headcounts.
Republicans had condemned the unionist moves in Fermanagh-South Tyrone, as well as the efforts to select a further agreed unionist candidate in South Belfast.