Up to 20 supporters of Fianna Fáil councillor Kate Feeney are to be denied a vote in next week's much-anticipated selection convention in Dun Laoghaire.
A tranche of newly registered Feeney supporters will be told that they cannot vote in the selection convention because they have been party members for less than a year.
The votes, seen as being crucial to Ms Feeney's chances at the convention, become active on October 1 - 2 days after the convention.
Party sources believe that without the votes, Ms Feeney could finish in third place behind councillor Cormac Devlin and former minister Mary Hanafin.
The news is the latest twist in the so-called "Battle of Blackrock".
But in further developments in recent days, independent.ie can reveal:
- Mr Devlin has sought legal advice amid fears he will fall victim to "gendermandering"
- Ms Hanafin told colleagues she wants the convention held as soon as possible due to the level of media attention
- Senior party figures agonise over who to add to ticket in the event of a Devlin victory
- Councillor Jennifer Cuffe's move to contest the Wicklow convention causes uproar among members
The convention next week is widely expected to be won by Mr Devlin. Informed party sources say it is unlikely a diktat will be issued for a female only ticket - similar to the events surrounding Dublin South Central and Dublin Central this week.
Nonetheless, Mr Devlin has sought legal advice amid fears he will be "gendermandered".
But given the issue surrounding Ms Feeney's 20 votes, it is likely that she will finish third to Mr Devlin and Ms Hanafin.
The decision to stage the convention in October - therefore excluding Feeney's 20 new supporters - infuriated the young councillor.
She told a Sunday newspaper that the move is "very unfair".
Independent.ie can reveal that party headquarters initially set the convention date for September 21 - prompting an immediate objection from the Feeney camp.
All three candidates held an informal meeting during which Ms Hanafin said the convention has attracted too much media attention.
Sources have predicted that Mr Devlin will win the convention and that Ms Hanafin will then be added to the ticket after finishing second.
Any prospect of issuing a diktat for an all female ticket has decreased as a result of the backlash the party received after blocking councillor Daithi de Roiste from running in Dublin South Central.
Catherine Ardagh will effectively run unopposed. However, the decision to block Mr de Roiste is expected to lead to a very heated selection convention as his supporters vent their fury over the decision.
The party also stopped male candidates from running in Dublin Central in a move that paves the way for former councillor Mary Fitzpatrick.
Party leader Micheal Martin will be relieved once the convention result is finalised. He has claimed on a number of occasions that the media is "fascinated" with the Dun Laoghaire constituency.
In a move that attracted little attention, cllr Jennifer Cuffe opted out of Dun Laoghaire and submitted a nomination in Wicklow/East Carlow.
Party members in Wicklow are furious at the move and have pointed to the fact that she does not serve the area.