An Alliance representative for Newry and Armagh has quit the party.
Jackie Coade was the party's candidate for the constituency in May's Stormont Assembly election.
She has stood for election for Alliance several times over the years and was credited with reviving the party's local membership.
Read more: Analysis: December Stormont Assembly election will only deepen divisions
Ms Coade, who has been an Alliance member for seven years, confirmed she has quit the party in recent weeks but said she did not wish to comment further.
The Alliance Party declined to comment.
Ms Coade featured prominently in Alliance's televised election broadcast ahead of the Assembly poll in May.
She was also among the election candidates who spoke from the podium at the party's annual conference in Belfast some months earlier.
A profile of Ms Coade on the Alliance Party website for the Assembly election campaign describes her as having a "strong sense of social justice".
It added: "Jackie has stood for election with the party several times before after reviving a local association which has a growing membership."
Her departure comes at a time when the party has been growing its vote share in the Newry and Armagh constituency.
Ms Coade was unsuccessful in her election bid in May but more than doubled her first-preference votes from 1,418 (2.6%) in 2017 to 3,345 (5.7%) this year.
The UK government has assumed a legal responsibility to call a fresh Assembly poll within 12 weeks after a legislative timeframe to restore Stormont lapsed last Friday.
But there has been continuing uncertainty over whether Secretary of State Chris Heaton-Harris will call an election.
He failed to set a date for a new poll last Friday, despite saying he would do so the minute the deadline passed.
READ NEXT:
NI secretary to provide a further update on next steps 'in due course'
'No clarity' from NI secretary on election, Stormont parties say
- DUP's Jeffrey Donaldson met Jamie Bryson 'days before bid to halt Brexit Protocol checks'
- DUP leader's claim that Brexit Protocol 'delayed heart surgery' dismissed by Belfast Trust
For all the latest news, visit the Belfast Live homepage here. To sign up to our FREE newsletters, see here.