Fianna Fail TD Eamon O'Cuiv says the party is facing an existential threat.
The Galway West TD believes the decline of the party will continue if it continues to blame external factors and not its own direction.
It comes as Fianna Fail is now at its lowest popularity rating according to the latest opinion poll.
The Taoiseach's party is now at 10 percent nationally, whereas in Dublin it is at 4 percent according to the Business Post / Red C survey.
Fine Gael is the most popular at 37 percent, while Sinn Fein is on 27 percent.