Sinn Féin has said it will not run candidates in three Northern Ireland constituencies in December's general election.
The party will not stand in South Belfast, East Belfast or North Down.
It is urging its voters to back the pro-remain candidates in those constituencies.
It comes after the SDLP announced it will not contest the Westminster seat in North Belfast for the first time in the party's history.
It is one of three constituencies which it will not fight in a bid to secure the seat for pro-remain candidates.
The other two constituencies are East Belfast and North Down.
.@MaryLouMcDonald says “you can call this a pact if you wish”, says stakes are high and this is about returning as many pro-remain MPs as possible. She says Sinn Féin want to see Lady Hermon returned in North Down and Naomi Long in East Belfast— Jayne McCormack (@BBCJayneMcC) November 4, 2019
Announcing its decision not to stand in three constituencies on Monday, Sinn Féin leader Mary-Lou McDonald said the party had been supportive of a pro-remain pact for some time and said "the stakes are high".
She said Sinn Féin wants to see SDLP's Claire Hanna returned in South Belfast, Naomi Long returned for Alliance in East Belfast and independent unionist Lady Hermon returned in North Down.
The party described it as a "positive development" and that voters wanted to see pro-remain parties support each other.
On Sunday, SDLP deputy leader Nichola Mallon said the objective "must be to return as many pro-remain MPs who will take their seats and vote to stop Brexit".
The North Belfast MLA added her party "must also seek to weaken those who have cast the interests of Northern Ireland aside for five minutes of influence with a Tory government that has been bad for our communities".
Ms Mallon said that meant "removing pro-Brexit, pro-Boris DUP MPs where possible".
The SDLP is not the only party which has decided not to stand for election in North Belfast.
On Sunday, the Ulster Unionist Party confirmed it will not field a candidate in the constituency where the choice was the sitting DUP MP Nigel Dodds or "an abstentionist MP" from Sinn Féin.
UUP leader-elect Steve Aiken had initially ruled out a DUP election pact - but later came under pressure from high-profile unionists who said the UUP must avoid splitting the unionist vote in North Belfast.