Green Party leader Clare Bailey is set to contest the EU election next month, the Belfast Telegraph can reveal.
With the SDLP or Alliance possibly in contention with the Ulster Unionists for the last of Northern Ireland's three seats, the Greens' plans remained unclear.
But party sources last night said that Ms Bailey, who became leader six months ago, will definitely stand in the poll.
Alliance leader Naomi Long also seems certain to contest the election with an announcement expected later this week.
Senior SDLP figures have indicated that their party leader Colum Eastwood will be running as well. The decision by Mrs Long and Mr Eastwood to stand in the normally low-key EU poll reflects how significant the election has become in light of Brexit and the belief that there may be two pro-Remain seats.
It is a high-risk strategy for the SDLP leader given the criticism he has faced for his party's link up with Fianna Fail.
In the 2014 EU elections, the Greens won almost 11,000 votes with then Belfast councillor Ross Brown as the candidate.
They came in just ahead of NI21 with Alliance candidate Anna Lo polling 44,000 votes.
Sinn Fein's Martina Anderson and the DUP's Diane Dodds are on course to take the first two seats with former UUP MLA Danny Kennedy replacing sitting MEP Jim Nicholson as his party's candidate. Mr Kennedy will be favourite to retain the seat but the party needs a strong performance in the council election three weeks earlier.
TUV leader Jim Allister hasn't yet announced his intentions. He polled 76,000 votes to the UUP's 83,000 in 2014 and can't be ruled out as a possible contender for the third seat if he runs.
The SDLP polled 82,000 votes in the 2014 poll, significantly ahead of Alliance. But with Mrs Long as a candidate, her party would expect to significantly close that gap or even overtake the SDLP. As with the UUP, much will depend on how both parties perform in the council elections. Mr Eastwood will need his party's vote to hold up well if he is to be in the running.
Alliance is hoping that the local government poll provides a bounce and believe that Mrs Long's popularity beyond the party faithful will significantly maximise its EU vote.
Alliance is launching its local government manifesto today and the Greens will do so tomorrow.
Ms Bailey, a South Belfast MLA, was unopposed for the Green leadership last year, taking over from Mr Agnew who had held the position for seven years.