FIANNA Fail chiefs have instructed that just one candidate be chosen at the party's selection convention in the high-profile Dublin Bay North constituency.
Party members will gather at Clontarf Castle tonight where former junior minister Sean Haughey will be challenged for a place on the general election ticket by sitting councillors Deirdre Heney and Tom Brabazon.
Aileen Woods, the daughter of former minister Michael Woods, is also vying for a place on the ticket.
She is based on the opposite side of the constituency to both Mr Haughey and Ms Heney.
Ms Woods was unsuccessful in a bid to get elected to Dublin City Council last year.
Party sources said she is likely to be handed Mr Haughey's Dublin City Council seat if he is elected to the Dail.
The selection convention is being held just weeks after Senator Averil Power shocked her colleagues by quitting the party.
Ms Power, who has not ruled out running as an independent, strongly criticised members of the Fianna Fail frontbench for their failure to campaign for a Yes vote in the Marriage Equality referendum.
She also accused party leader Micheal Martin of being a "leader without followers".
Despite her departure, the party received a poll boost in last weekend's Behaviour and Analysis poll for the Sunday Times.
In a letter to members of the Dublin Bay North branch, Fianna Fail general secretary Sean Dorgan issued a diktat that just one candidate be selected.
He said the strategy was decided by the party's National Constituencies Committee, which is chaired by Cork North West TD Michael Moynihan.
Mr Dorgan pointed out that the party has moved to a one-member one-vote system following a decision taken at the Fianna Fail Ard Fheis.
Party sources said Mr Haughey, who is son of the late Taoiseach Charles Haughey, is confident that he has the numbers to win convention.
However, Mr Brabazon and Ms Heney have both been phoning delegates in recent days seeking their support.
The party is likely to await the result of the convention before deciding whether to add a second candidate.
The outcome of the poll is likely to be one of the most difficult to call in the capital.
Six sitting TDs, including two ministers, are competing for just five seats. Key to Ms Power's decision to run or not will be whether she can bring a significant portion of her Fianna Fail support base with her as an independent.
Labour is unlikely to keep both of its seats, held by junior minister Aodhan O Riordain and backbencher Sean Kenny.
Fine Gael is fielding Jobs Minister Richard Bruton, former Lord Mayor Naoise O Muiri and Stephanie Regan.
That wasn't the original plan, however. A three-candidate strategy was improvised after Mr Bruton suffered a shock defeat at his own selection convention.
Fine Gael sources claimed it happened due to delegates' anger at the party deciding that a female candidate would be on the ticket to satisfy gender quotas.
Also in Dublin Bay North, Independent TDs Tommy Broughan and Finian McGrath are expected to take seats.
Renua Ireland is adamant that its TD Terence Flanagan has a strong chance of holding on to his seat as well. Smart money will be on Sinn Fein to take a seat through either councillor Micheal MacDonncha or Denise Mitchell.
Left-wing groups could spring a surprise in the constituency. Michael O'Brien is representing the Anti-Austerity Alliance, while John Lyons is the People Before Profit candidate.