The Green Party has extended its decision not to run in favour of other pro-EU candidates to all four Belfast constituencies.
In what is another blow for DUP MPs Nigel Dodds, Emma Little Pengelly and Gavin Robinson, the Greens have now withdrawn in favour of their opponents.
The move is likely to be particularly significant in North Belfast where both the SDLP and the Greens are now backing Sinn Fein’s John Finucane.
DUP deputy leader Mr Dodds only had a 2,000 votes majority over SF in 2017.
Between them, the Greens and the SDLP took 2,700 votes in 2017 – and since then the Green vote has risen significantly.
The Greens are now backing the SDLP in South Belfast, Sinn Fein in North and West Belfast and Alliance in East Belfast.
The party has not clarified whether it will also stand aside in favour of a pro-Remain party in North Down, or whether it will run.
New Green Party leader Clare Bailey’s acceptance of a pro-Remain pact is in contrast to a rejection of such an arrangement under her predecessor, Steven Agnew.
In a statement yesterday, Ms Bailey said: “This election is all about returning as many pro-Remain MPs as possible.
“These are extraordinary times and require an extraordinary response.
“The Green Party NI achieved our best ever vote across the city of Belfast in the local government election earlier this year.
“However, I’m prepared to put the need to have pro-Remain MPs returned ahead of party interest.
“The realities of the first-past-the-post system and the threat posed to our way of life by Brexit means that we must do everything possible to maximise the pro-Remain vote.”
In 2017, when it was suggested that there should be a similar pro-Remain pact, Mr Agnew outlined a series of reasons why he believed it was wrong to stand aside for other parties.
The then North Down MLA, who stepped down as leader last year and then left the Assembly earlier this year, said: “The Green Party will not enter into a pact for the forthcoming Westminster election.
“The decision has followed discussion amongst party members and our party executive. We also met with the SDLP, Sinn Fein and the UUP as parties who had previously taken a pro-Remain stance.
“The Green Party has a clear vision for a progressive society based on stability and sustainability. We cannot enter into a pact with parties and individual candidates that fall short of that.”
He said that the SDLP’s choice of Alasdair McDonnell in that election had been a problem.
He also said: “We also met with Sinn Fein about a pro-Remain pact. However, they failed to provide any indication that they would take their Westminster seats.
“It is impossible to oppose hard Brexit at every turn without taking seats in Parliament.
“We did meet with the UUP but it is clear that they have abandoned their pro-Remain principles”.