The four contenders for the leadership of Fianna Fail will put their cases for support today.
Ahead of a secret ballot on Wednesday and with former foreign affairs minister Micheal Martin the favourite, the candidates will lobby party TDs for votes.
Mr Martin faces a challenge from Finance Minister Brian Lenihan, Tourism and Enterprise Minister Mary Hanafin and Social Protection and Defence Minister Eamon O Cuiv at the parliamentary party meeting.
The new leader, the eighth since the party was founded in 1926, will be elected after a 2pm vote on Wednesday in the party rooms in Leinster House.
Party chairman John Browne confirmed all four contenders had been officially nominated for the leadership contest.
Mr Martin, from Cork, was proposed by Dara Calleary and seconded by Aine Brady.
The rebel TD, who failed in a heave against Mr Cowen last week, has insisted he has the energy, passion and commitment to lead Fianna Fail into a General Election and beyond.
Dublin-based Mr Lenihan, who is battling cancer, was proposed by Sean Connick and seconded by Thomas Byrne.
He put Fine Gael and Labour on notice that, with him at the helm of Fianna Fail, the election campaign will be no walkover, warning he will fight them in every corner of the country.
Ms Hanafin was proposed by Cabinet colleague Pat Carey and seconded by Maire Hoctor.
The Dun Laoghaire TD said she wants to lead a renewed movement which encourages young people and women.
Mr O Cuiv, originally from Dublin but a Galway TD, aspires to follow in the footsteps of his grandfather Eamon De Valera, founder of Fianna Fail and the country's first taoiseach.
He was proposed by Eamon Scanlon and seconded by Michael Kitt.